It turns out that 'access()' (and 'faccessat()') can cause a lot of RCU
work because it installs a temporary credential that gets allocated and
freed for each system call.
The allocation and freeing overhead is mostly benign, but because
credentials can be accessed under the RCU read lock, the freeing
involves a RCU grace period.
Which is not a huge deal normally, but if you have a lot of access()
calls, this causes a fair amount of seconday damage: instead of having a
nice alloc/free patterns that hits in hot per-CPU slab caches, you have
all those delayed free's, and on big machines with hundreds of cores,
the RCU overhead can end up being enormous.
But it turns out that all of this is entirely unnecessary. Exactly
because access() only installs the credential as the thread-local
subjective credential, the temporary cred pointer doesn't actually need
to be RCU free'd at all. Once we're done using it, we can just free it
synchronously and avoid all the RCU overhead.
So add a 'non_rcu' flag to 'struct cred', which can be set by users that
know they only use it in non-RCU context (there are other potential
users for this). We can make it a union with the rcu freeing list head
that we need for the RCU case, so this doesn't need any extra storage.
Note that this also makes 'get_current_cred()' clear the new non_rcu
flag, in case we have filesystems that take a long-term reference to the
cred and then expect the RCU delayed freeing afterwards. It's not
entirely clear that this is required, but it makes for clear semantics:
the subjective cred remains non-RCU as long as you only access it
synchronously using the thread-local accessors, but you _can_ use it as
a generic cred if you want to.
It is possible that we should just remove the whole RCU markings for
->cred entirely. Only ->real_cred is really supposed to be accessed
through RCU, and the long-term cred copies that nfs uses might want to
explicitly re-enable RCU freeing if required, rather than have
get_current_cred() do it implicitly.
But this is a "minimal semantic changes" change for the immediate
problem.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Jan Glauber <jglauber@marvell.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Jayachandran Chandrasekharan Nair <jnair@marvell.com>
Cc: Greg KH <greg@kroah.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add SPDX license identifiers to all files which:
- Have no license information of any form
- Have EXPORT_.*_SYMBOL_GPL inside which was used in the
initial scan/conversion to ignore the file
These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:
GPL-2.0-only
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This amends commit 10dce8af34 ("fs: stream_open - opener for
stream-like files so that read and write can run simultaneously without
deadlock") in how position is passed into .read()/.write() handler for
stream-like files:
Rasmus noticed that we currently pass 0 as position and ignore any position
change if that is done by a file implementation. This papers over bugs if ppos
is used in files that declare themselves as being stream-like as such bugs will
go unnoticed. Even if a file implementation is correctly converted into using
stream_open, its read/write later could be changed to use ppos and even though
that won't be working correctly, that bug might go unnoticed without someone
doing wrong behaviour analysis. It is thus better to pass ppos=NULL into
read/write for stream-like files as that don't give any chance for ppos usage
bugs because it will oops if ppos is ever used inside .read() or .write().
Note 1: rw_verify_area, new_sync_{read,write} needs to be updated
because they are called by vfs_read/vfs_write & friends before
file_operations .read/.write .
Note 2: if file backend uses new-style .read_iter/.write_iter, position
is still passed into there as non-pointer kiocb.ki_pos . Currently
stream_open.cocci (semantic patch added by 10dce8af34) ignores files
whose file_operations has *_iter methods.
Suggested-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Kirill Smelkov <kirr@nexedi.com>
Commit 9c225f2655 ("vfs: atomic f_pos accesses as per POSIX") added
locking for file.f_pos access and in particular made concurrent read and
write not possible - now both those functions take f_pos lock for the
whole run, and so if e.g. a read is blocked waiting for data, write will
deadlock waiting for that read to complete.
This caused regression for stream-like files where previously read and
write could run simultaneously, but after that patch could not do so
anymore. See e.g. commit 581d21a2d0 ("xenbus: fix deadlock on writes
to /proc/xen/xenbus") which fixes such regression for particular case of
/proc/xen/xenbus.
The patch that added f_pos lock in 2014 did so to guarantee POSIX thread
safety for read/write/lseek and added the locking to file descriptors of
all regular files. In 2014 that thread-safety problem was not new as it
was already discussed earlier in 2006.
However even though 2006'th version of Linus's patch was adding f_pos
locking "only for files that are marked seekable with FMODE_LSEEK (thus
avoiding the stream-like objects like pipes and sockets)", the 2014
version - the one that actually made it into the tree as 9c225f2655 -
is doing so irregardless of whether a file is seekable or not.
See
https://lore.kernel.org/lkml/53022DB1.4070805@gmail.com/https://lwn.net/Articles/180387https://lwn.net/Articles/180396
for historic context.
The reason that it did so is, probably, that there are many files that
are marked non-seekable, but e.g. their read implementation actually
depends on knowing current position to correctly handle the read. Some
examples:
kernel/power/user.c snapshot_read
fs/debugfs/file.c u32_array_read
fs/fuse/control.c fuse_conn_waiting_read + ...
drivers/hwmon/asus_atk0110.c atk_debugfs_ggrp_read
arch/s390/hypfs/inode.c hypfs_read_iter
...
Despite that, many nonseekable_open users implement read and write with
pure stream semantics - they don't depend on passed ppos at all. And for
those cases where read could wait for something inside, it creates a
situation similar to xenbus - the write could be never made to go until
read is done, and read is waiting for some, potentially external, event,
for potentially unbounded time -> deadlock.
Besides xenbus, there are 14 such places in the kernel that I've found
with semantic patch (see below):
drivers/xen/evtchn.c:667:8-24: ERROR: evtchn_fops: .read() can deadlock .write()
drivers/isdn/capi/capi.c:963:8-24: ERROR: capi_fops: .read() can deadlock .write()
drivers/input/evdev.c:527:1-17: ERROR: evdev_fops: .read() can deadlock .write()
drivers/char/pcmcia/cm4000_cs.c:1685:7-23: ERROR: cm4000_fops: .read() can deadlock .write()
net/rfkill/core.c:1146:8-24: ERROR: rfkill_fops: .read() can deadlock .write()
drivers/s390/char/fs3270.c:488:1-17: ERROR: fs3270_fops: .read() can deadlock .write()
drivers/usb/misc/ldusb.c:310:1-17: ERROR: ld_usb_fops: .read() can deadlock .write()
drivers/hid/uhid.c:635:1-17: ERROR: uhid_fops: .read() can deadlock .write()
net/batman-adv/icmp_socket.c:80:1-17: ERROR: batadv_fops: .read() can deadlock .write()
drivers/media/rc/lirc_dev.c:198:1-17: ERROR: lirc_fops: .read() can deadlock .write()
drivers/leds/uleds.c:77:1-17: ERROR: uleds_fops: .read() can deadlock .write()
drivers/input/misc/uinput.c:400:1-17: ERROR: uinput_fops: .read() can deadlock .write()
drivers/infiniband/core/user_mad.c:985:7-23: ERROR: umad_fops: .read() can deadlock .write()
drivers/gnss/core.c:45:1-17: ERROR: gnss_fops: .read() can deadlock .write()
In addition to the cases above another regression caused by f_pos
locking is that now FUSE filesystems that implement open with
FOPEN_NONSEEKABLE flag, can no longer implement bidirectional
stream-like files - for the same reason as above e.g. read can deadlock
write locking on file.f_pos in the kernel.
FUSE's FOPEN_NONSEEKABLE was added in 2008 in a7c1b990f7 ("fuse:
implement nonseekable open") to support OSSPD. OSSPD implements /dev/dsp
in userspace with FOPEN_NONSEEKABLE flag, with corresponding read and
write routines not depending on current position at all, and with both
read and write being potentially blocking operations:
See
https://github.com/libfuse/osspdhttps://lwn.net/Articles/308445https://github.com/libfuse/osspd/blob/14a9cff0/osspd.c#L1406https://github.com/libfuse/osspd/blob/14a9cff0/osspd.c#L1438-L1477https://github.com/libfuse/osspd/blob/14a9cff0/osspd.c#L1479-L1510
Corresponding libfuse example/test also describes FOPEN_NONSEEKABLE as
"somewhat pipe-like files ..." with read handler not using offset.
However that test implements only read without write and cannot exercise
the deadlock scenario:
https://github.com/libfuse/libfuse/blob/fuse-3.4.2-3-ga1bff7d/example/poll.c#L124-L131https://github.com/libfuse/libfuse/blob/fuse-3.4.2-3-ga1bff7d/example/poll.c#L146-L163https://github.com/libfuse/libfuse/blob/fuse-3.4.2-3-ga1bff7d/example/poll.c#L209-L216
I've actually hit the read vs write deadlock for real while implementing
my FUSE filesystem where there is /head/watch file, for which open
creates separate bidirectional socket-like stream in between filesystem
and its user with both read and write being later performed
simultaneously. And there it is semantically not easy to split the
stream into two separate read-only and write-only channels:
https://lab.nexedi.com/kirr/wendelin.core/blob/f13aa600/wcfs/wcfs.go#L88-169
Let's fix this regression. The plan is:
1. We can't change nonseekable_open to include &~FMODE_ATOMIC_POS -
doing so would break many in-kernel nonseekable_open users which
actually use ppos in read/write handlers.
2. Add stream_open() to kernel to open stream-like non-seekable file
descriptors. Read and write on such file descriptors would never use
nor change ppos. And with that property on stream-like files read and
write will be running without taking f_pos lock - i.e. read and write
could be running simultaneously.
3. With semantic patch search and convert to stream_open all in-kernel
nonseekable_open users for which read and write actually do not
depend on ppos and where there is no other methods in file_operations
which assume @offset access.
4. Add FOPEN_STREAM to fs/fuse/ and open in-kernel file-descriptors via
steam_open if that bit is present in filesystem open reply.
It was tempting to change fs/fuse/ open handler to use stream_open
instead of nonseekable_open on just FOPEN_NONSEEKABLE flags, but
grepping through Debian codesearch shows users of FOPEN_NONSEEKABLE,
and in particular GVFS which actually uses offset in its read and
write handlers
https://codesearch.debian.net/search?q=-%3Enonseekable+%3Dhttps://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1080https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1247-1346https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1399-1481
so if we would do such a change it will break a real user.
5. Add stream_open and FOPEN_STREAM handling to stable kernels starting
from v3.14+ (the kernel where 9c225f2655 first appeared).
This will allow to patch OSSPD and other FUSE filesystems that
provide stream-like files to return FOPEN_STREAM | FOPEN_NONSEEKABLE
in their open handler and this way avoid the deadlock on all kernel
versions. This should work because fs/fuse/ ignores unknown open
flags returned from a filesystem and so passing FOPEN_STREAM to a
kernel that is not aware of this flag cannot hurt. In turn the kernel
that is not aware of FOPEN_STREAM will be < v3.14 where just
FOPEN_NONSEEKABLE is sufficient to implement streams without read vs
write deadlock.
This patch adds stream_open, converts /proc/xen/xenbus to it and adds
semantic patch to automatically locate in-kernel places that are either
required to be converted due to read vs write deadlock, or that are just
safe to be converted because read and write do not use ppos and there
are no other funky methods in file_operations.
Regarding semantic patch I've verified each generated change manually -
that it is correct to convert - and each other nonseekable_open instance
left - that it is either not correct to convert there, or that it is not
converted due to current stream_open.cocci limitations.
The script also does not convert files that should be valid to convert,
but that currently have .llseek = noop_llseek or generic_file_llseek for
unknown reason despite file being opened with nonseekable_open (e.g.
drivers/input/mousedev.c)
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Yongzhi Pan <panyongzhi@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Tejun Heo <tj@kernel.org>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Julia Lawall <Julia.Lawall@lip6.fr>
Cc: Nikolaus Rath <Nikolaus@rath.org>
Cc: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Kirill Smelkov <kirr@nexedi.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
syzbot is hitting lockdep warning [1] due to trying to open a fifo
during an execve() operation. But we don't need to open non regular
files during an execve() operation, for all files which we will need are
the executable file itself and the interpreter programs like /bin/sh and
ld-linux.so.2 .
Since the manpage for execve(2) says that execve() returns EACCES when
the file or a script interpreter is not a regular file, and the manpage
for uselib(2) says that uselib() can return EACCES, and we use
FMODE_EXEC when opening for execve()/uselib(), we can bail out if a non
regular file is requested with FMODE_EXEC set.
Since this deadlock followed by khungtaskd warnings is trivially
reproducible by a local unprivileged user, and syzbot's frequent crash
due to this deadlock defers finding other bugs, let's workaround this
deadlock until we get a chance to find a better solution.
[1] https://syzkaller.appspot.com/bug?id=b5095bfec44ec84213bac54742a82483aad578ce
Link: http://lkml.kernel.org/r/1552044017-7890-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
Reported-by: syzbot <syzbot+e93a80c1bb7c5c56e522461c149f8bf55eab1b2b@syzkaller.appspotmail.com>
Fixes: 8924feff66 ("splice: lift pipe_lock out of splice_to_pipe()")
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org> [4.9+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This contains two new features:
1) Stack file operations: this allows removal of several hacks from the
VFS, proper interaction of read-only open files with copy-up,
possibility to implement fs modifying ioctls properly, and others.
2) Metadata only copy-up: when file is on lower layer and only metadata is
modified (except size) then only copy up the metadata and continue to
use the data from the lower file.
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Merge tag 'ovl-update-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs
Pull overlayfs updates from Miklos Szeredi:
"This contains two new features:
- Stack file operations: this allows removal of several hacks from
the VFS, proper interaction of read-only open files with copy-up,
possibility to implement fs modifying ioctls properly, and others.
- Metadata only copy-up: when file is on lower layer and only
metadata is modified (except size) then only copy up the metadata
and continue to use the data from the lower file"
* tag 'ovl-update-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs: (66 commits)
ovl: Enable metadata only feature
ovl: Do not do metacopy only for ioctl modifying file attr
ovl: Do not do metadata only copy-up for truncate operation
ovl: add helper to force data copy-up
ovl: Check redirect on index as well
ovl: Set redirect on upper inode when it is linked
ovl: Set redirect on metacopy files upon rename
ovl: Do not set dentry type ORIGIN for broken hardlinks
ovl: Add an inode flag OVL_CONST_INO
ovl: Treat metacopy dentries as type OVL_PATH_MERGE
ovl: Check redirects for metacopy files
ovl: Move some dir related ovl_lookup_single() code in else block
ovl: Do not expose metacopy only dentry from d_real()
ovl: Open file with data except for the case of fsync
ovl: Add helper ovl_inode_realdata()
ovl: Store lower data inode in ovl_inode
ovl: Fix ovl_getattr() to get number of blocks from lower
ovl: Add helper ovl_dentry_lowerdata() to get lower data dentry
ovl: Copy up meta inode data from lowest data inode
ovl: Modify ovl_lookup() and friends to lookup metacopy dentry
...
This reverts commit 4d0c5ba2ff.
We now get write access on both overlay and underlying layers so this patch
is no longer needed for correct operation.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This reverts commit 7c6893e3c9.
Overlayfs no longer relies on the vfs for checking writability of files.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Let overlayfs do its thing when opening a file.
This enables stacking and fixes the corner case when a file is opened for
read, modified through a writable open, and data is read from the read-only
file. After this patch the read-only open will not return stale data even
in this case.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Stacking file operations in overlay will store an extra open file for each
overlay file opened.
The overhead is just that of "struct file" which is about 256bytes, because
overlay already pins an extra dentry and inode when the file is open, which
add up to a much larger overhead.
For fear of breaking working setups, don't start accounting the extra file.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
open a file by given inode, faking ->f_path. Use with shitloads
of caution - at the very least you'd damn better make sure that
some dentry alias of that inode is pinned down by the path in
question. Again, this is no general-purpose interface and I hope
it will eventually go away. Right now overlayfs wants something
like that, but nothing else should.
Any out-of-tree code with bright idea of using this one *will*
eventually get hurt, with zero notice and great delight on my part.
I refuse to use EXPORT_SYMBOL_GPL(), especially in situations when
it's really EXPORT_SYMBOL_DONT_USE_IT(), but don't take that export
as "you are welcome to use it".
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
FMODE_OPENED can be used to distingusish "successful open" from the
"called finish_no_open(), do it yourself" cases. Since finish_no_open()
has been adjusted, no changes in the instances were actually needed.
The caller has been adjusted.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
... and don't bother with setting FILE_OPENED at all.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
These checks are better off in do_dentry_open(); the reason we couldn't
put them there used to be that callers couldn't tell what kind of cleanup
would do_dentry_open() failure call for. Now that we have FMODE_OPENED,
cleanup is the same in all cases - it's simply fput(). So let's fold
that into do_dentry_open(), as Christoph's patch tried to.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Just check FMODE_OPENED in __fput() and be done with that...
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
basically, "is that instance set up enough for regular fput(), or
do we want put_filp() for that one".
NOTE: the only alloc_file() caller that could be followed by put_filp()
is in arch/ia64/kernel/perfmon.c, which is (Kconfig-level) broken.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
... and rename get_empty_filp() to alloc_empty_file().
dentry_open() gets creds as argument, but the only thing that sees those is
security_file_open() - file->f_cred still ends up with current_cred(). For
almost all callers it's the same thing, but there are several broken cases.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
An ->open() instances really, really should not be doing that. There's
a lot of places e.g. around atomic_open() that could be confused by that,
so let's catch that early.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
it's exactly the same thing as
dentry_open(&file->f_path, file->f_flags, file->f_cred)
... and rename it to file_clone_open(), while we are at it.
'filp' naming convention is bogus; sure, it's "file pointer",
but we generally don't do that kind of Hungarian notation.
Some of the instances have too many callers to touch, but this
one has only two, so let's sanitize it while we can...
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This reverts commit cab64df194.
Having vfs_open() in some cases drop the reference to
struct file combined with
error = vfs_open(path, f, cred);
if (error) {
put_filp(f);
return ERR_PTR(error);
}
return f;
is flat-out wrong. It used to be
error = vfs_open(path, f, cred);
if (!error) {
/* from now on we need fput() to dispose of f */
error = open_check_o_direct(f);
if (error) {
fput(f);
f = ERR_PTR(error);
}
} else {
put_filp(f);
f = ERR_PTR(error);
}
and sure, having that open_check_o_direct() boilerplate gotten rid of is
nice, but not that way...
Worse, another call chain (via finish_open()) is FUBAR now wrt
FILE_OPENED handling - in that case we get error returned, with file
already hit by fput() *AND* FILE_OPENED not set. Guess what happens in
path_openat(), when it hits
if (!(opened & FILE_OPENED)) {
BUG_ON(!error);
put_filp(file);
}
The root cause of all that crap is that the callers of do_dentry_open()
have no way to tell which way did it fail; while that could be fixed up
(by passing something like int *opened to do_dentry_open() and have it
marked if we'd called ->open()), it's probably much too late in the
cycle to do so right now.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Using the ksys_fallocate() wrapper allows us to get rid of in-kernel
calls to the sys_fallocate() syscall. The ksys_ prefix denotes that this
function is meant as a drop-in replacement for the syscall. In
particular, it uses the same calling convention as sys_fallocate().
This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Using the ksys_truncate() wrapper allows us to get rid of in-kernel
calls to the sys_truncate() syscall. The ksys_ prefix denotes that this
function is meant as a drop-in replacement for the syscall. In
particular, it uses the same calling convention as sys_truncate().
This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Using this wrapper allows us to avoid the in-kernel calls to the
sys_open() syscall. The ksys_ prefix denotes that this function is meant
as a drop-in replacement for the syscall. In particular, it uses the
same calling convention as sys_open().
This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Using the ksys_close() wrapper allows us to get rid of in-kernel calls
to the sys_close() syscall. The ksys_ prefix denotes that this function
is meant as a drop-in replacement for the syscall. In particular, it
uses the same calling convention as sys_close(), with one subtle
difference:
The few places which checked the return value did not care about the return
value re-writing in sys_close(), so simply use a wrapper around
__close_fd().
This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Using the ksys_ftruncate() wrapper allows us to get rid of in-kernel
calls to the sys_ftruncate() syscall. The ksys_ prefix denotes that this
function is meant as a drop-in replacement for the syscall. In
particular, it uses the same calling convention as sys_ftruncate().
This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Using the fs-interal do_fchownat() wrapper allows us to get rid of
fs-internal calls to the sys_fchownat() syscall.
Introducing the ksys_fchown() helper and the ksys_{,}chown() wrappers
allows us to avoid the in-kernel calls to the sys_{,l,f}chown() syscalls.
The ksys_ prefix denotes that these functions are meant as a drop-in
replacement for the syscalls. In particular, they use the same calling
convention as sys_{,l,f}chown().
This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Using the fs-internal do_faccessat() helper allows us to get rid of
fs-internal calls to the sys_faccessat() syscall.
Introducing the ksys_access() wrapper allows us to avoid the in-kernel
calls to the sys_access() syscall. The ksys_ prefix denotes that this
function is meant as a drop-in replacement for the syscall. In
particular, it uses the same calling convention as sys_access().
This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Using the fs-internal do_fchmodat() helper allows us to get rid of
fs-internal calls to the sys_fchmodat() syscall.
Introducing the ksys_fchmod() helper and the ksys_chmod() wrapper allows
us to avoid the in-kernel calls to the sys_fchmod() and sys_chmod()
syscalls. The ksys_ prefix denotes that these functions are meant as a
drop-in replacement for the syscalls. In particular, they use the same
calling convention as sys_fchmod() and sys_chmod().
This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Using this helper allows us to avoid the in-kernel calls to the sys_chdir()
syscall. The ksys_ prefix denotes that this function is meant as a drop-in
replacement for the syscall. In particular, it uses the same calling
convention as sys_chdir().
This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Using this helper allows us to avoid the in-kernel calls to the
sys_chroot() syscall. The ksys_ prefix denotes that this function is
meant as a drop-in replacement for the syscall. In particular, it uses the
same calling convention as sys_chroot().
In the near future, the fs-external callers of ksys_chroot() should be
converted to use kern_path()/set_fs_root() directly. Then ksys_chroot()
can be moved within sys_chroot() again.
This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
do_dentry_open is where we do the actual open of the file, so this is
where we should do our O_DIRECT sanity check to cover all potential
callers.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Problem with ioctl() is that it's a file operation, yet often used as an
inode operation (i.e. modify the inode despite the file being opened for
read-only).
mnt_want_write_file() is used by filesystems in such cases to get write
access on an arbitrary open file.
Since overlayfs lets filesystems do all file operations, including ioctl,
this can lead to mnt_want_write_file() returning OK for a lower file and
modification of that lower file.
This patch prevents modification by checking if the file is from an
overlayfs lower layer and returning EPERM in that case.
Need to introduce a mnt_want_write_file_path() variant that still does the
old thing for inode operations that can do the copy up + modification
correctly in such cases (fchown, fsetxattr, fremovexattr).
This does not address the correctness of such ioctls on overlayfs (the
correct way would be to copy up and attempt to perform ioctl on upper
file).
In theory this could be a regression. We very much hope that nobody is
relying on such a hack in any sane setup.
While this patch meddles in VFS code, it has no effect on non-overlayfs
filesystems.
Reported-by: "zhangyi (F)" <yi.zhang@huawei.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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Merge tag 'for-linus-v4.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux
Pull Writeback error handling updates from Jeff Layton:
"This pile represents the bulk of the writeback error handling fixes
that I have for this cycle. Some of the earlier patches in this pile
may look trivial but they are prerequisites for later patches in the
series.
The aim of this set is to improve how we track and report writeback
errors to userland. Most applications that care about data integrity
will periodically call fsync/fdatasync/msync to ensure that their
writes have made it to the backing store.
For a very long time, we have tracked writeback errors using two flags
in the address_space: AS_EIO and AS_ENOSPC. Those flags are set when a
writeback error occurs (via mapping_set_error) and are cleared as a
side-effect of filemap_check_errors (as you noted yesterday). This
model really sucks for userland.
Only the first task to call fsync (or msync or fdatasync) will see the
error. Any subsequent task calling fsync on a file will get back 0
(unless another writeback error occurs in the interim). If I have
several tasks writing to a file and calling fsync to ensure that their
writes got stored, then I need to have them coordinate with one
another. That's difficult enough, but in a world of containerized
setups that coordination may even not be possible.
But wait...it gets worse!
The calls to filemap_check_errors can be buried pretty far down in the
call stack, and there are internal callers of filemap_write_and_wait
and the like that also end up clearing those errors. Many of those
callers ignore the error return from that function or return it to
userland at nonsensical times (e.g. truncate() or stat()). If I get
back -EIO on a truncate, there is no reason to think that it was
because some previous writeback failed, and a subsequent fsync() will
(incorrectly) return 0.
This pile aims to do three things:
1) ensure that when a writeback error occurs that that error will be
reported to userland on a subsequent fsync/fdatasync/msync call,
regardless of what internal callers are doing
2) report writeback errors on all file descriptions that were open at
the time that the error occurred. This is a user-visible change,
but I think most applications are written to assume this behavior
anyway. Those that aren't are unlikely to be hurt by it.
3) document what filesystems should do when there is a writeback
error. Today, there is very little consistency between them, and a
lot of cargo-cult copying. We need to make it very clear what
filesystems should do in this situation.
To achieve this, the set adds a new data type (errseq_t) and then
builds new writeback error tracking infrastructure around that. Once
all of that is in place, we change the filesystems to use the new
infrastructure for reporting wb errors to userland.
Note that this is just the initial foray into cleaning up this mess.
There is a lot of work remaining here:
1) convert the rest of the filesystems in a similar fashion. Once the
initial set is in, then I think most other fs' will be fairly
simple to convert. Hopefully most of those can in via individual
filesystem trees.
2) convert internal waiters on writeback to use errseq_t for
detecting errors instead of relying on the AS_* flags. I have some
draft patches for this for ext4, but they are not quite ready for
prime time yet.
This was a discussion topic this year at LSF/MM too. If you're
interested in the gory details, LWN has some good articles about this:
https://lwn.net/Articles/718734/https://lwn.net/Articles/724307/"
* tag 'for-linus-v4.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux:
btrfs: minimal conversion to errseq_t writeback error reporting on fsync
xfs: minimal conversion to errseq_t writeback error reporting
ext4: use errseq_t based error handling for reporting data writeback errors
fs: convert __generic_file_fsync to use errseq_t based reporting
block: convert to errseq_t based writeback error tracking
dax: set errors in mapping when writeback fails
Documentation: flesh out the section in vfs.txt on storing and reporting writeback errors
mm: set both AS_EIO/AS_ENOSPC and errseq_t in mapping_set_error
fs: new infrastructure for writeback error handling and reporting
lib: add errseq_t type and infrastructure for handling it
mm: don't TestClearPageError in __filemap_fdatawait_range
mm: clear AS_EIO/AS_ENOSPC when writeback initiation fails
jbd2: don't clear and reset errors after waiting on writeback
buffer: set errors in mapping at the time that the error occurs
fs: check for writeback errors after syncing out buffers in generic_file_fsync
buffer: use mapping_set_error instead of setting the flag
mm: fix mapping_set_error call in me_pagecache_dirty
Most filesystems currently use mapping_set_error and
filemap_check_errors for setting and reporting/clearing writeback errors
at the mapping level. filemap_check_errors is indirectly called from
most of the filemap_fdatawait_* functions and from
filemap_write_and_wait*. These functions are called from all sorts of
contexts to wait on writeback to finish -- e.g. mostly in fsync, but
also in truncate calls, getattr, etc.
The non-fsync callers are problematic. We should be reporting writeback
errors during fsync, but many places spread over the tree clear out
errors before they can be properly reported, or report errors at
nonsensical times.
If I get -EIO on a stat() call, there is no reason for me to assume that
it is because some previous writeback failed. The fact that it also
clears out the error such that a subsequent fsync returns 0 is a bug,
and a nasty one since that's potentially silent data corruption.
This patch adds a small bit of new infrastructure for setting and
reporting errors during address_space writeback. While the above was my
original impetus for adding this, I think it's also the case that
current fsync semantics are just problematic for userland. Most
applications that call fsync do so to ensure that the data they wrote
has hit the backing store.
In the case where there are multiple writers to the file at the same
time, this is really hard to determine. The first one to call fsync will
see any stored error, and the rest get back 0. The processes with open
fds may not be associated with one another in any way. They could even
be in different containers, so ensuring coordination between all fsync
callers is not really an option.
One way to remedy this would be to track what file descriptor was used
to dirty the file, but that's rather cumbersome and would likely be
slow. However, there is a simpler way to improve the semantics here
without incurring too much overhead.
This set adds an errseq_t to struct address_space, and a corresponding
one is added to struct file. Writeback errors are recorded in the
mapping's errseq_t, and the one in struct file is used as the "since"
value.
This changes the semantics of the Linux fsync implementation such that
applications can now use it to determine whether there were any
writeback errors since fsync(fd) was last called (or since the file was
opened in the case of fsync having never been called).
Note that those writeback errors may have occurred when writing data
that was dirtied via an entirely different fd, but that's the case now
with the current mapping_set_error/filemap_check_error infrastructure.
This will at least prevent you from getting a false report of success.
The new behavior is still consistent with the POSIX spec, and is more
reliable for application developers. This patch just adds some basic
infrastructure for doing this, and ensures that the f_wb_err "cursor"
is properly set when a file is opened. Later patches will change the
existing code to use this new infrastructure for reporting errors at
fsync time.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Define a set of write life time hints:
RWH_WRITE_LIFE_NOT_SET No hint information set
RWH_WRITE_LIFE_NONE No hints about write life time
RWH_WRITE_LIFE_SHORT Data written has a short life time
RWH_WRITE_LIFE_MEDIUM Data written has a medium life time
RWH_WRITE_LIFE_LONG Data written has a long life time
RWH_WRITE_LIFE_EXTREME Data written has an extremely long life time
The intent is for these values to be relative to each other, no
absolute meaning should be attached to these flag names.
Add an fcntl interface for querying these flags, and also for
setting them as well:
F_GET_RW_HINT Returns the read/write hint set on the
underlying inode.
F_SET_RW_HINT Set one of the above write hints on the
underlying inode.
F_GET_FILE_RW_HINT Returns the read/write hint set on the
file descriptor.
F_SET_FILE_RW_HINT Set one of the above write hints on the
file descriptor.
The user passes in a 64-bit pointer to get/set these values, and
the interface returns 0/-1 on success/error.
Sample program testing/implementing basic setting/getting of write
hints is below.
Add support for storing the write life time hint in the inode flags
and in struct file as well, and pass them to the kiocb flags. If
both a file and its corresponding inode has a write hint, then we
use the one in the file, if available. The file hint can be used
for sync/direct IO, for buffered writeback only the inode hint
is available.
This is in preparation for utilizing these hints in the block layer,
to guide on-media data placement.
/*
* writehint.c: get or set an inode write hint
*/
#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdbool.h>
#include <inttypes.h>
#ifndef F_GET_RW_HINT
#define F_LINUX_SPECIFIC_BASE 1024
#define F_GET_RW_HINT (F_LINUX_SPECIFIC_BASE + 11)
#define F_SET_RW_HINT (F_LINUX_SPECIFIC_BASE + 12)
#endif
static char *str[] = { "RWF_WRITE_LIFE_NOT_SET", "RWH_WRITE_LIFE_NONE",
"RWH_WRITE_LIFE_SHORT", "RWH_WRITE_LIFE_MEDIUM",
"RWH_WRITE_LIFE_LONG", "RWH_WRITE_LIFE_EXTREME" };
int main(int argc, char *argv[])
{
uint64_t hint;
int fd, ret;
if (argc < 2) {
fprintf(stderr, "%s: file <hint>\n", argv[0]);
return 1;
}
fd = open(argv[1], O_RDONLY);
if (fd < 0) {
perror("open");
return 2;
}
if (argc > 2) {
hint = atoi(argv[2]);
ret = fcntl(fd, F_SET_RW_HINT, &hint);
if (ret < 0) {
perror("fcntl: F_SET_RW_HINT");
return 4;
}
}
ret = fcntl(fd, F_GET_RW_HINT, &hint);
if (ret < 0) {
perror("fcntl: F_GET_RW_HINT");
return 3;
}
printf("%s: hint %s\n", argv[1], str[hint]);
close(fd);
return 0;
}
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull misc vfs updates from Al Viro:
"Making sure that something like a referral point won't end up as pwd
or root.
The main part is the last commit (fixing mntns_install()); that one
fixes a hard-to-hit race. The fchdir() commit is making fchdir(2) a
bit more robust - it should be impossible to get opened files (even
O_PATH ones) for referral points in the first place, so the existing
checks are OK, but checking the same thing as in chdir(2) is just as
cheap.
The path_init() commit removes a redundant check that shouldn't have
been there in the first place"
* 'work.sane_pwd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
make sure that mntns_install() doesn't end up with referral for root
path_init(): don't bother with checking MAY_EXEC for LOOKUP_ROOT
make sure that fchdir() won't accept referral points, etc.
Pull overlayfs update from Miklos Szeredi:
"The biggest part of this is making st_dev/st_ino on the overlay behave
like a normal filesystem (i.e. st_ino doesn't change on copy up,
st_dev is the same for all files and directories). Currently this only
works if all layers are on the same filesystem, but future work will
move the general case towards more sane behavior.
There are also miscellaneous fixes, including fixes to handling
append-only files. There's a small change in the VFS, but that only
has an effect on overlayfs, since otherwise file->f_path.dentry->inode
and file_inode(file) are always the same"
* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
ovl: update documentation w.r.t. constant inode numbers
ovl: persistent inode numbers for upper hardlinks
ovl: merge getattr for dir and nondir
ovl: constant st_ino/st_dev across copy up
ovl: persistent inode number for directories
ovl: set the ORIGIN type flag
ovl: lookup non-dir copy-up-origin by file handle
ovl: use an auxiliary var for overlay root entry
ovl: store file handle of lower inode on copy up
ovl: check if all layers are on the same fs
ovl: do not set overlay.opaque on non-dir create
ovl: check IS_APPEND() on real upper inode
vfs: ftruncate check IS_APPEND() on real upper inode
ovl: Use designated initializers
ovl: lockdep annotate of nested stacked overlayfs inode lock
Pull misc vfs updates from Al Viro:
"Assorted bits and pieces from various people. No common topic in this
pile, sorry"
* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fs/affs: add rename exchange
fs/affs: add rename2 to prepare multiple methods
Make stat/lstat/fstatat pass AT_NO_AUTOMOUNT to vfs_statx()
fs: don't set *REFERENCED on single use objects
fs: compat: Remove warning from COMPATIBLE_IOCTL
remove pointless extern of atime_need_update_rcu()
fs: completely ignore unknown open flags
fs: add a VALID_OPEN_FLAGS
fs: remove _submit_bh()
fs: constify tree_descr arrays passed to simple_fill_super()
fs: drop duplicate header percpu-rwsem.h
fs/affs: bugfix: Write files greater than page size on OFS
fs/affs: bugfix: enable writes on OFS disks
fs/affs: remove node generation check
fs/affs: import amigaffs.h
fs/affs: bugfix: make symbolic links work again
Currently we just stash anything we got into file->f_flags, and the
report it in fcntl(F_GETFD). This patch just clears out all unknown
flags so that we don't pass them to the fs or report them.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
ftruncate an overlayfs inode was checking IS_APPEND() on
overlay inode, but overlay inode does not have the S_APPEND flag.
Check IS_APPEND() on real upper inode instead.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Before calling write f_ops, call file_start_write() instead
of sb_start_write().
Replace {sb,file}_start_write() for {copy,clone}_file_range() and
for fallocate().
Beyond correct semantics, this avoids freeze protection to sb when
operating on special inodes, such as fallocate() on a blockdev.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
There was an obscure use case of fallocate of directory inode
in the vfs helper with the comment:
"Let individual file system decide if it supports preallocation
for directories or not."
But there is no in-tree file system that implements fallocate
for directory operations.
Deny an attempt to fallocate a directory with EISDIR error.
This change is needed prior to converting sb_start_write()
to file_start_write(), so freeze protection is correctly
handled for cases of fallocate file and blockdev.
Cc: linux-api@vger.kernel.org
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This was entirely automated, using the script by Al:
PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>'
sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \
$(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)
to do the replacement at the end of the merge window.
Requested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
< XFS has gained super CoW powers! >
----------------------------------
\ ^__^
\ (oo)\_______
(__)\ )\/\
||----w |
|| ||
Included in this update:
- unshare range (FALLOC_FL_UNSHARE) support for fallocate
- copy-on-write extent size hints (FS_XFLAG_COWEXTSIZE) for fsxattr interface
- shared extent support for XFS
- copy-on-write support for shared extents
- copy_file_range support
- clone_file_range support (implements reflink)
- dedupe_file_range support
- defrag support for reverse mapping enabled filesystems
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Merge tag 'xfs-reflink-for-linus-4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs
< XFS has gained super CoW powers! >
----------------------------------
\ ^__^
\ (oo)\_______
(__)\ )\/\
||----w |
|| ||
Pull XFS support for shared data extents from Dave Chinner:
"This is the second part of the XFS updates for this merge cycle. This
pullreq contains the new shared data extents feature for XFS.
Given the complexity and size of this change I am expecting - like the
addition of reverse mapping last cycle - that there will be some
follow-up bug fixes and cleanups around the -rc3 stage for issues that
I'm sure will show up once the code hits a wider userbase.
What it is:
At the most basic level we are simply adding shared data extents to
XFS - i.e. a single extent on disk can now have multiple owners. To do
this we have to add new on-disk features to both track the shared
extents and the number of times they've been shared. This is done by
the new "refcount" btree that sits in every allocation group. When we
share or unshare an extent, this tree gets updated.
Along with this new tree, the reverse mapping tree needs to be updated
to track each owner or a shared extent. This also needs to be updated
ever share/unshare operation. These interactions at extent allocation
and freeing time have complex ordering and recovery constraints, so
there's a significant amount of new intent-based transaction code to
ensure that operations are performed atomically from both the runtime
and integrity/crash recovery perspectives.
We also need to break sharing when writes hit a shared extent - this
is where the new copy-on-write implementation comes in. We allocate
new storage and copy the original data along with the overwrite data
into the new location. We only do this for data as we don't share
metadata at all - each inode has it's own metadata that tracks the
shared data extents, the extents undergoing CoW and it's own private
extents.
Of course, being XFS, nothing is simple - we use delayed allocation
for CoW similar to how we use it for normal writes. ENOSPC is a
significant issue here - we build on the reservation code added in
4.8-rc1 with the reverse mapping feature to ensure we don't get
spurious ENOSPC issues part way through a CoW operation. These
mechanisms also help minimise fragmentation due to repeated CoW
operations. To further reduce fragmentation overhead, we've also
introduced a CoW extent size hint, which indicates how large a region
we should allocate when we execute a CoW operation.
With all this functionality in place, we can hook up .copy_file_range,
.clone_file_range and .dedupe_file_range and we gain all the
capabilities of reflink and other vfs provided functionality that
enable manipulation to shared extents. We also added a fallocate mode
that explicitly unshares a range of a file, which we implemented as an
explicit CoW of all the shared extents in a file.
As such, it's a huge chunk of new functionality with new on-disk
format features and internal infrastructure. It warns at mount time as
an experimental feature and that it may eat data (as we do with all
new on-disk features until they stabilise). We have not released
userspace suport for it yet - userspace support currently requires
download from Darrick's xfsprogs repo and build from source, so the
access to this feature is really developer/tester only at this point.
Initial userspace support will be released at the same time the kernel
with this code in it is released.
The new code causes 5-6 new failures with xfstests - these aren't
serious functional failures but things the output of tests changing
slightly due to perturbations in layouts, space usage, etc. OTOH,
we've added 150+ new tests to xfstests that specifically exercise this
new functionality so it's got far better test coverage than any
functionality we've previously added to XFS.
Darrick has done a pretty amazing job getting us to this stage, and
special mention also needs to go to Christoph (review, testing,
improvements and bug fixes) and Brian (caught several intricate bugs
during review) for the effort they've also put in.
Summary:
- unshare range (FALLOC_FL_UNSHARE) support for fallocate
- copy-on-write extent size hints (FS_XFLAG_COWEXTSIZE) for fsxattr
interface
- shared extent support for XFS
- copy-on-write support for shared extents
- copy_file_range support
- clone_file_range support (implements reflink)
- dedupe_file_range support
- defrag support for reverse mapping enabled filesystems"
* tag 'xfs-reflink-for-linus-4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs: (71 commits)
xfs: convert COW blocks to real blocks before unwritten extent conversion
xfs: rework refcount cow recovery error handling
xfs: clear reflink flag if setting realtime flag
xfs: fix error initialization
xfs: fix label inaccuracies
xfs: remove isize check from unshare operation
xfs: reduce stack usage of _reflink_clear_inode_flag
xfs: check inode reflink flag before calling reflink functions
xfs: implement swapext for rmap filesystems
xfs: refactor swapext code
xfs: various swapext cleanups
xfs: recognize the reflink feature bit
xfs: simulate per-AG reservations being critically low
xfs: don't mix reflink and DAX mode for now
xfs: check for invalid inode reflink flags
xfs: set a default CoW extent size of 32 blocks
xfs: convert unwritten status of reverse mappings for shared files
xfs: use interval query for rmap alloc operations on shared files
xfs: add shared rmap map/unmap/convert log item types
xfs: increase log reservations for reflink
...
After much discussion, it seems that the fallocate feature flag
FALLOC_FL_ZERO_RANGE maps nicely to SCSI WRITE SAME; and the feature
FALLOC_FL_PUNCH_HOLE maps nicely to the devices that have been whitelisted
for zeroing SCSI UNMAP. Punch still requires that FALLOC_FL_KEEP_SIZE is
set. A length that goes past the end of the device will be clamped to the
device size if KEEP_SIZE is set; or will return -EINVAL if not. Both
start and length must be aligned to the device's logical block size.
Since the semantics of fallocate are fairly well established already, wire
up the two pieces. The other fallocate variants (collapse range, insert
range, and allocate blocks) are not supported.
Link: http://lkml.kernel.org/r/147518379992.22791.8849838163218235007.stgit@birch.djwong.org
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Mike Snitzer <snitzer@redhat.com> # tweaked header
Cc: Brian Foster <bfoster@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add a new fallocate mode flag that explicitly unshares blocks on
filesystems that support such features. The new flag can only
be used with an allocate-mode fallocate call.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
The problem with writecount is: we want consistent handling of it for
underlying filesystems as well as overlayfs. Making sure i_writecount is
correct on all layers is difficult. Instead this patch makes sure that
when write access is acquired, it's always done on the underlying writable
layer (called the upper layer). We must also make sure to look at the
writecount on this layer when checking for conflicting leases.
Open for write already updates the upper layer's writecount. Leaving only
truncate.
For truncate copy up must happen before get_write_access() so that the
writecount is updated on the upper layer. Problem with this is if
something fails after that, then copy-up was done needlessly. E.g. if
break_lease() was interrupted. Probably not a big deal in practice.
Another interesting case is if there's a denywrite on a lower file that is
then opened for write or truncated. With this patch these will succeed,
which is somewhat counterintuitive. But I think it's still acceptable,
considering that the copy-up does actually create a different file, so the
old, denywrite mapping won't be touched.
On non-overlayfs d_real() is an identity function and d_real_inode() is
equivalent to d_inode() so this patch doesn't change behavior in that case.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Acked-by: Jeff Layton <jlayton@poochiereds.net>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
This patch allows flock, posix locks, ofd locks and leases to work
correctly on overlayfs.
Instead of using the underlying inode for storing lock context use the
overlay inode. This allows locks to be persistent across copy-up.
This is done by introducing locks_inode() helper and using it instead of
file_inode() to get the inode in locking code. For non-overlayfs the two
are equivalent, except for an extra pointer dereference in locks_inode().
Since lock operations are in "struct file_operations" we must also make
sure not to call underlying filesystem's lock operations. Introcude a
super block flag MS_NOREMOTELOCK to this effect.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Acked-by: Jeff Layton <jlayton@poochiereds.net>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
First off, the intention of this pull is to declare that I'll be the
binfmt_misc maintainer (mainly on the grounds of you touched it last,
it's yours). There's no MAINTAINERS entry, but get_maintainers.pl
will now finger me.
The update itself is to allow architecture emulation containers to
function such that the emulation binary can be housed outside the
container itself. The container and fs parts both have acks from
relevant experts.
The change is user visible. To use the new feature you have to add an
F option to your binfmt_misc configuration. However, the existing
tools, like systemd-binfmt work with this without modification.
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
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Merge tag 'binfmt-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/binfmt_misc
Pull binfmt_misc update from James Bottomley:
"This update is to allow architecture emulation containers to function
such that the emulation binary can be housed outside the container
itself. The container and fs parts both have acks from relevant
experts.
To use the new feature you have to add an F option to your binfmt_misc
configuration"
From the docs:
"The usual behaviour of binfmt_misc is to spawn the binary lazily when
the misc format file is invoked. However, this doesn't work very well
in the face of mount namespaces and changeroots, so the F mode opens
the binary as soon as the emulation is installed and uses the opened
image to spawn the emulator, meaning it is always available once
installed, regardless of how the environment changes"
* tag 'binfmt-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/binfmt_misc:
binfmt_misc: add F option description to documentation
binfmt_misc: add persistent opened binary handler for containers
fs: add filp_clone_open API
The two methods essentially do the same: find the real dentry/inode
belonging to an overlay dentry. The difference is in the usage:
vfs_open() uses ->d_select_inode() and expects the function to perform
copy-up if necessary based on the open flags argument.
file_dentry() uses ->d_real() passing in the overlay dentry as well as the
underlying inode.
vfs_rename() uses ->d_select_inode() but passes zero flags. ->d_real()
with a zero inode would have worked just as well here.
This patch merges the functionality of ->d_select_inode() into ->d_real()
by adding an 'open_flags' argument to the latter.
[Al Viro] Make the signature of d_real() match that of ->d_real() again.
And constify the inode argument, while we are at it.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Pull 'struct path' constification update from Al Viro:
"'struct path' is passed by reference to a bunch of Linux security
methods; in theory, there's nothing to stop them from modifying the
damn thing and LSM community being what it is, sooner or later some
enterprising soul is going to decide that it's a good idea.
Let's remove the temptation and constify all of those..."
* 'work.const-path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
constify ima_d_path()
constify security_sb_pivotroot()
constify security_path_chroot()
constify security_path_{link,rename}
apparmor: remove useless checks for NULL ->mnt
constify security_path_{mkdir,mknod,symlink}
constify security_path_{unlink,rmdir}
apparmor: constify common_perm_...()
apparmor: constify aa_path_link()
apparmor: new helper - common_path_perm()
constify chmod_common/security_path_chmod
constify security_sb_mount()
constify chown_common/security_path_chown
tomoyo: constify assorted struct path *
apparmor_path_truncate(): path->mnt is never NULL
constify vfs_truncate()
constify security_path_truncate()
[apparmor] constify struct path * in a bunch of helpers
Backmerge to resolve a conflict in ovl_lookup_real();
"ovl_lookup_real(): use lookup_one_len_unlocked()" instead,
but it was too late in the cycle to rebase.
I need an API that allows me to obtain a clone of the current file
pointer to pass in to an exec handler. I've labelled this as an
internal API because I can't see how it would be useful outside of the
fs subsystem. The use case will be a persistent binfmt_misc handler.
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Acked-by: Jan Kara <jack@suse.cz>
This commit fixes the following security hole affecting systems where
all of the following conditions are fulfilled:
- The fs.suid_dumpable sysctl is set to 2.
- The kernel.core_pattern sysctl's value starts with "/". (Systems
where kernel.core_pattern starts with "|/" are not affected.)
- Unprivileged user namespace creation is permitted. (This is
true on Linux >=3.8, but some distributions disallow it by
default using a distro patch.)
Under these conditions, if a program executes under secure exec rules,
causing it to run with the SUID_DUMP_ROOT flag, then unshares its user
namespace, changes its root directory and crashes, the coredump will be
written using fsuid=0 and a path derived from kernel.core_pattern - but
this path is interpreted relative to the root directory of the process,
allowing the attacker to control where a coredump will be written with
root privileges.
To fix the security issue, always interpret core_pattern for dumps that
are written under SUID_DUMP_ROOT relative to the root directory of init.
Signed-off-by: Jann Horn <jann@thejh.net>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
parallel to mutex_{lock,unlock,trylock,is_locked,lock_nested},
inode_foo(inode) being mutex_foo(&inode->i_mutex).
Please, use those for access to ->i_mutex; over the coming cycle
->i_mutex will become rwsem, with ->lookup() done with it held
only shared.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Today proc and sysfs do not contain any executable files. Several
applications today mount proc or sysfs without noexec and nosuid and
then depend on there being no exectuables files on proc or sysfs.
Having any executable files show on proc or sysfs would cause
a user space visible regression, and most likely security problems.
Therefore commit to never allowing executables on proc and sysfs by
adding a new flag to mark them as filesystems without executables and
enforce that flag.
Test the flag where MNT_NOEXEC is tested today, so that the only user
visible effect will be that exectuables will be treated as if the
execute bit is cleared.
The filesystems proc and sysfs do not currently incoporate any
executable files so this does not result in any user visible effects.
This makes it unnecessary to vet changes to proc and sysfs tightly for
adding exectuable files or changes to chattr that would modify
existing files, as no matter what the individual file say they will
not be treated as exectuable files by the vfs.
Not having to vet changes to closely is important as without this we
are only one proc_create call (or another goof up in the
implementation of notify_change) from having problematic executables
on proc. Those mistakes are all too easy to make and would create
a situation where there are security issues or the assumptions of
some program having to be broken (and cause userspace regressions).
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Comment in include/linux/security.h says that ->inode_killpriv() should
be called when setuid bit is being removed and that similar security
labels (in fact this applies only to file capabilities) should be
removed at this time as well. However we don't call ->inode_killpriv()
when we remove suid bit on truncate.
We fix the problem by calling ->inode_need_killpriv() and subsequently
->inode_killpriv() on truncate the same way as we do it on file write.
After this patch there's only one user of should_remove_suid() - ocfs2 -
and indeed it's buggy because it doesn't call ->inode_killpriv() on
write. However fixing it is difficult because of special locking
constraints.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Make file->f_path always point to the overlay dentry so that the path in
/proc/pid/fd is correct and to ensure that label-based LSMs have access to the
overlay as well as the underlay (path-based LSMs probably don't need it).
Using my union testsuite to set things up, before the patch I see:
[root@andromeda union-testsuite]# bash 5</mnt/a/foo107
[root@andromeda union-testsuite]# ls -l /proc/$$/fd/
...
lr-x------. 1 root root 64 Jun 5 14:38 5 -> /a/foo107
[root@andromeda union-testsuite]# stat /mnt/a/foo107
...
Device: 23h/35d Inode: 13381 Links: 1
...
[root@andromeda union-testsuite]# stat -L /proc/$$/fd/5
...
Device: 23h/35d Inode: 13381 Links: 1
...
After the patch:
[root@andromeda union-testsuite]# bash 5</mnt/a/foo107
[root@andromeda union-testsuite]# ls -l /proc/$$/fd/
...
lr-x------. 1 root root 64 Jun 5 14:22 5 -> /mnt/a/foo107
[root@andromeda union-testsuite]# stat /mnt/a/foo107
...
Device: 23h/35d Inode: 40346 Links: 1
...
[root@andromeda union-testsuite]# stat -L /proc/$$/fd/5
...
Device: 23h/35d Inode: 40346 Links: 1
...
Note the change in where /proc/$$/fd/5 points to in the ls command. It was
pointing to /a/foo107 (which doesn't exist) and now points to /mnt/a/foo107
(which is correct).
The inode accessed, however, is the lower layer. The union layer is on device
25h/37d and the upper layer on 24h/36d.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Make use of d_backing_inode() in pathwalk to gain access to an
inode or dentry that's on a lower layer.
Signed-off-by: David Howells <dhowells@redhat.com>
This update contains:
o RENAME_WHITEOUT support
o conversion of per-cpu superblock accounting to use generic counters
o new inode mmap lock so that we can lock page faults out of truncate, hole
punch and other direct extent manipulation functions to avoid racing mmap
writes from causing data corruption
o rework of direct IO submission and completion to solve data corruption issue
when running concurrent extending DIO writes. Also solves problem of running
IO completion transactions in interrupt context during size extending AIO
writes.
o FALLOC_FL_INSERT_RANGE support for inserting holes into a file via direct
extent manipulation to avoid needing to copy data within the file
o attribute block header field overflow fix for 64k block size filesystems
o Lots of changes to log messaging to be more informative and concise when
errors occur. Also prevent a lot of unnecessary log spamming due to cascading
failures in error conditions.
o lots of cleanups and bug fixes
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Merge tag 'xfs-for-linus-4.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs
Pull xfs update from Dave Chinner:
"This update contains:
- RENAME_WHITEOUT support
- conversion of per-cpu superblock accounting to use generic counters
- new inode mmap lock so that we can lock page faults out of
truncate, hole punch and other direct extent manipulation functions
to avoid racing mmap writes from causing data corruption
- rework of direct IO submission and completion to solve data
corruption issue when running concurrent extending DIO writes.
Also solves problem of running IO completion transactions in
interrupt context during size extending AIO writes.
- FALLOC_FL_INSERT_RANGE support for inserting holes into a file via
direct extent manipulation to avoid needing to copy data within the
file
- attribute block header field overflow fix for 64k block size
filesystems
- Lots of changes to log messaging to be more informative and concise
when errors occur. Also prevent a lot of unnecessary log spamming
due to cascading failures in error conditions.
- lots of cleanups and bug fixes
One thing of note is the direct IO fixes that we merged last week
after the window opened. Even though a little late, they fix a user
reported data corruption and have been pretty well tested. I figured
there was not much point waiting another 2 weeks for -rc1 to be
released just so I could send them to you..."
* tag 'xfs-for-linus-4.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs: (49 commits)
xfs: using generic_file_direct_write() is unnecessary
xfs: direct IO EOF zeroing needs to drain AIO
xfs: DIO write completion size updates race
xfs: DIO writes within EOF don't need an ioend
xfs: handle DIO overwrite EOF update completion correctly
xfs: DIO needs an ioend for writes
xfs: move DIO mapping size calculation
xfs: factor DIO write mapping from get_blocks
xfs: unlock i_mutex in xfs_break_layouts
xfs: kill unnecessary firstused overflow check on attr3 leaf removal
xfs: use larger in-core attr firstused field and detect overflow
xfs: pass attr geometry to attr leaf header conversion functions
xfs: disallow ro->rw remount on norecovery mount
xfs: xfs_shift_file_space can be static
xfs: Add support FALLOC_FL_INSERT_RANGE for fallocate
fs: Add support FALLOC_FL_INSERT_RANGE for fallocate
xfs: Fix incorrect positive ENOMEM return
xfs: xfs_mru_cache_insert() should use GFP_NOFS
xfs: %pF is only for function pointers
xfs: fix shadow warning in xfs_da3_root_split()
...
We have observed a BUG() crash in fs/attr.c:notify_change(). The crash
occurs during an rsync into a filesystem that is exported via NFS.
1.) fs/attr.c:notify_change() modifies the caller's version of attr.
2.) 6de0ec00ba ("VFS: make notify_change pass ATTR_KILL_S*ID to
setattr operations") introduced a BUG() restriction such that "no
function will ever call notify_change() with both ATTR_MODE and
ATTR_KILL_S*ID set". Under some circumstances though, it will have
assisted in setting the caller's version of attr to this very
combination.
3.) 27ac0ffeac ("locks: break delegations on any attribute
modification") introduced code to handle breaking
delegations. This can result in notify_change() being re-called. attr
_must_ be explicitly reset to avoid triggering the BUG() established
in #2.
4.) The path that that triggers this is via fs/open.c:chmod_common().
The combination of attr flags set here and in the first call to
notify_change() along with a later failed break_deleg_wait()
results in notify_change() being called again via retry_deleg
without resetting attr.
Solution is to move retry_deleg in chmod_common() a bit further up to
ensure attr is completely reset.
There are other places where this seemingly could occur, such as
fs/utimes.c:utimes_common(), but the attr flags are not initially
set in such a way to trigger this.
Fixes: 27ac0ffeac ("locks: break delegations on any attribute modification")
Reported-by: Eric Meddaugh <etmsys@rit.edu>
Tested-by: Eric Meddaugh <etmsys@rit.edu>
Signed-off-by: Andrew Elble <aweits@rit.edu>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
For one thing, LOOKUP_DIRECTORY will be dealt with in do_last().
For another, name can be an empty string, but not NULL - no callers
pass that and it would oops immediately if they would.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
FALLOC_FL_INSERT_RANGE command is the opposite command of
FALLOC_FL_COLLAPSE_RANGE that is needed for someone who wants to add
some data in the middle of file.
FALLOC_FL_INSERT_RANGE will create space for writing new data within
a file after shifting extents to right as given length. This command
also has same limitations as FALLOC_FL_COLLAPSE_RANGE in that
operations need to be filesystem block boundary aligned and cannot
cross the current EOF.
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Ashish Sangwan <a.sangwan@samsung.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Pull getname/putname updates from Al Viro:
"Rework of getname/getname_kernel/etc., mostly from Paul Moore. Gets
rid of quite a pile of kludges between namei and audit..."
* 'getname2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
audit: replace getname()/putname() hacks with reference counters
audit: fix filename matching in __audit_inode() and __audit_inode_child()
audit: enable filename recording via getname_kernel()
simpler calling conventions for filename_mountpoint()
fs: create proper filename objects using getname_kernel()
fs: rework getname_kernel to handle up to PATH_MAX sized filenames
cut down the number of do_path_lookup() callers
All callers of get_xip_mem() are now gone. Remove checks for it,
initialisers of it, documentation of it and the only implementation of it.
Also remove mm/filemap_xip.c as it is now empty. Also remove
documentation of the long-gone get_xip_page().
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Andreas Dilger <andreas.dilger@intel.com>
Cc: Boaz Harrosh <boaz@plexistor.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are several areas in the kernel that create temporary filename
objects using the following pattern:
int func(const char *name)
{
struct filename *file = { .name = name };
...
return 0;
}
... which for the most part works okay, but it causes havoc within the
audit subsystem as the filename object does not persist beyond the
lifetime of the function. This patch converts all of these temporary
filename objects into proper filename objects using getname_kernel()
and putname() which ensure that the filename object persists until the
audit subsystem is finished with it.
Also, a special thanks to Al Viro, Guenter Roeck, and Sabrina Dubroca
for helping resolve a difficult kernel panic on boot related to a
use-after-free problem in kern_path_create(); the thread can be seen
at the link below:
* https://lkml.org/lkml/2015/1/20/710
This patch includes code that was either based on, or directly written
by Al in the above thread.
CC: viro@zeniv.linux.org.uk
CC: linux@roeck-us.net
CC: sd@queasysnail.net
CC: linux-fsdevel@vger.kernel.org
Signed-off-by: Paul Moore <pmoore@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull nfsd updates from Bruce Fields:
"A comparatively quieter cycle for nfsd this time, but still with two
larger changes:
- RPC server scalability improvements from Jeff Layton (using RCU
instead of a spinlock to find idle threads).
- server-side NFSv4.2 ALLOCATE/DEALLOCATE support from Anna
Schumaker, enabling fallocate on new clients"
* 'for-3.19' of git://linux-nfs.org/~bfields/linux: (32 commits)
nfsd4: fix xdr4 count of server in fs_location4
nfsd4: fix xdr4 inclusion of escaped char
sunrpc/cache: convert to use string_escape_str()
sunrpc: only call test_bit once in svc_xprt_received
fs: nfsd: Fix signedness bug in compare_blob
sunrpc: add some tracepoints around enqueue and dequeue of svc_xprt
sunrpc: convert to lockless lookup of queued server threads
sunrpc: fix potential races in pool_stats collection
sunrpc: add a rcu_head to svc_rqst and use kfree_rcu to free it
sunrpc: require svc_create callers to pass in meaningful shutdown routine
sunrpc: have svc_wake_up only deal with pool 0
sunrpc: convert sp_task_pending flag to use atomic bitops
sunrpc: move rq_cachetype field to better optimize space
sunrpc: move rq_splice_ok flag into rq_flags
sunrpc: move rq_dropme flag into rq_flags
sunrpc: move rq_usedeferral flag to rq_flags
sunrpc: move rq_local field to rq_flags
sunrpc: add a generic rq_flags field to svc_rqst and move rq_secure to it
nfsd: minor off by one checks in __write_versions()
sunrpc: release svc_pool_map reference when serv allocation fails
...
The fanotify and the inotify API can be used to monitor changes of the
file system. System call fallocate() modifies files. Hence it should
trigger the corresponding fanotify (FAN_MODIFY) and inotify (IN_MODIFY)
events. The most interesting case is FALLOC_FL_COLLAPSE_RANGE because
this value allows to create arbitrary file content from random data.
This patch adds the missing call to fsnotify_modify().
The FAN_MODIFY and IN_MODIFY event will be created when fallocate()
succeeds. It will even be created if the file length remains unchanged,
e.g. when calling fanotify with flag FALLOC_FL_KEEP_SIZE.
This logic was primarily chosen to keep the coding simple.
It resembles the logic of the write() system call.
When we call write() we always create a FAN_MODIFY event, even in the case
of overwriting with identical data.
Events FAN_MODIFY and IN_MODIFY do not provide any guarantee that data was
actually changed.
Furthermore even if if the filesize remains unchanged, fallocate() may
influence whether a subsequent write() will succeed and hence the
fallocate() call may be considered a modification.
The fallocate(2) man page teaches: After a successful call, subsequent
writes into the range specified by offset and len are guaranteed not to
fail because of lack of disk space.
So calling fallocate(fd, FALLOC_FL_KEEP_SIZE, offset, len) may result in
different outcomes of a subsequent write depending on the values of offset
and len.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Eric Paris <eparis@parisplace.org>
Cc: John McCutchan <john@johnmccutchan.com>
Cc: Robert Love <rlove@rlove.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
... for situations when we don't have any candidate in pathnames - basically,
in descriptor-based syscalls.
[Folded the build fix for !CONFIG_AUDITSYSCALL configs from Chen Gang]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This function needs to be exported so it can be used by the NFSD module
when responding to the new ALLOCATE and DEALLOCATE operations in NFS
v4.2. Christoph Hellwig suggested renaming the function to stay
consistent with how other vfs functions are named.
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Add a new inode operation i_op->dentry_open(). This is for stacked filesystems
that want to return a struct file from a different filesystem.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Fix the broken check for calling sys_fallocate() on an active swapfile,
introduced by commit 0790b31b69 ("fs: disallow all fallocate
operation on active swapfile").
Signed-off-by: Eric Biggers <ebiggers3@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Beginning to introduce those. Just the callers for now, and it's
clumsier than it'll eventually become; once we finish converting
aio_read and aio_write instances, the things will get nicer.
For now, these guys are in parallel to ->aio_read() and ->aio_write();
they take iocb and iov_iter, with everything in iov_iter already
validated. File offset is passed in iocb->ki_pos, iov/nr_segs -
in iov_iter.
Main concerns in that series are stack footprint and ability to
split the damn thing cleanly.
[fix from Peter Ujfalusi <peter.ujfalusi@ti.com> folded]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Since we are about to introduce new methods (read_iter/write_iter), the
tests in a bunch of places would have to grow inconveniently. Check
once (at open() time) and store results in ->f_mode as FMODE_CAN_READ
and FMODE_CAN_WRITE resp. It might end up being a temporary measure -
once everything switches from ->aio_{read,write} to ->{read,write}_iter
it might make sense to return to open-coded checks. We'll see...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We had a number of new features in ext4 during this merge window
(ZERO_RANGE and COLLAPSE_RANGE fallocate modes, renameat, etc.) so
there were many more regression and bug fixes this time around. It
didn't help that xfstests hadn't been fully updated to fully stress
test COLLAPSE_RANGE until after -rc1.
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Merge tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
Pull ext4 fixes from Ted Ts'o:
"These are regression and bug fixes for ext4.
We had a number of new features in ext4 during this merge window
(ZERO_RANGE and COLLAPSE_RANGE fallocate modes, renameat, etc.) so
there were many more regression and bug fixes this time around. It
didn't help that xfstests hadn't been fully updated to fully stress
test COLLAPSE_RANGE until after -rc1"
* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (31 commits)
ext4: disable COLLAPSE_RANGE for bigalloc
ext4: fix COLLAPSE_RANGE failure with 1KB block size
ext4: use EINVAL if not a regular file in ext4_collapse_range()
ext4: enforce we are operating on a regular file in ext4_zero_range()
ext4: fix extent merging in ext4_ext_shift_path_extents()
ext4: discard preallocations after removing space
ext4: no need to truncate pagecache twice in collapse range
ext4: fix removing status extents in ext4_collapse_range()
ext4: use filemap_write_and_wait_range() correctly in collapse range
ext4: use truncate_pagecache() in collapse range
ext4: remove temporary shim used to merge COLLAPSE_RANGE and ZERO_RANGE
ext4: fix ext4_count_free_clusters() with EXT4FS_DEBUG and bigalloc enabled
ext4: always check ext4_ext_find_extent result
ext4: fix error handling in ext4_ext_shift_extents
ext4: silence sparse check warning for function ext4_trim_extent
ext4: COLLAPSE_RANGE only works on extent-based files
ext4: fix byte order problems introduced by the COLLAPSE_RANGE patches
ext4: use i_size_read in ext4_unaligned_aio()
fs: disallow all fallocate operation on active swapfile
fs: move falloc collapse range check into the filesystem methods
...
Pull vfs updates from Al Viro:
"The first vfs pile, with deep apologies for being very late in this
window.
Assorted cleanups and fixes, plus a large preparatory part of iov_iter
work. There's a lot more of that, but it'll probably go into the next
merge window - it *does* shape up nicely, removes a lot of
boilerplate, gets rid of locking inconsistencie between aio_write and
splice_write and I hope to get Kent's direct-io rewrite merged into
the same queue, but some of the stuff after this point is having
(mostly trivial) conflicts with the things already merged into
mainline and with some I want more testing.
This one passes LTP and xfstests without regressions, in addition to
usual beating. BTW, readahead02 in ltp syscalls testsuite has started
giving failures since "mm/readahead.c: fix readahead failure for
memoryless NUMA nodes and limit readahead pages" - might be a false
positive, might be a real regression..."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (63 commits)
missing bits of "splice: fix racy pipe->buffers uses"
cifs: fix the race in cifs_writev()
ceph_sync_{,direct_}write: fix an oops on ceph_osdc_new_request() failure
kill generic_file_buffered_write()
ocfs2_file_aio_write(): switch to generic_perform_write()
ceph_aio_write(): switch to generic_perform_write()
xfs_file_buffered_aio_write(): switch to generic_perform_write()
export generic_perform_write(), start getting rid of generic_file_buffer_write()
generic_file_direct_write(): get rid of ppos argument
btrfs_file_aio_write(): get rid of ppos
kill the 5th argument of generic_file_buffered_write()
kill the 4th argument of __generic_file_aio_write()
lustre: don't open-code kernel_recvmsg()
ocfs2: don't open-code kernel_recvmsg()
drbd: don't open-code kernel_recvmsg()
constify blk_rq_map_user_iov() and friends
lustre: switch to kernel_sendmsg()
ocfs2: don't open-code kernel_sendmsg()
take iov_iter stuff to mm/iov_iter.c
process_vm_access: tidy up a bit
...
Currently some file system have IS_SWAPFILE check in their fallocate
implementations and some do not. However we should really prevent any
fallocate operation on swapfile so move the check to vfs and remove the
redundant checks from the file systems fallocate implementations.
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Currently in do_fallocate in collapse range case we're checking
whether offset + len is not bigger than i_size. However there is
nothing which would prevent i_size from changing so the check is
pointless. It should be done in the file system itself and the file
system needs to make sure that i_size is not going to change. The
i_size check for the other fallocate modes are also done in the
filesystems.
As it is now we can easily crash the kernel by having two processes
doing truncate and fallocate collapse range at the same time. This
can be reproduced on ext4 and it is theoretically possible on xfs even
though I was not able to trigger it with this simple test.
This commit removes the check from do_fallocate and adds it to the
file system.
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Acked-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Currently punch hole and collapse range fallocate operation are not
allowed on append only file. This should be case for zero range as well.
Fix it by allowing only pure fallocate (possibly with keep size set).
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
The main changes in the XFS tree for 3.15-rc1 are:
- O_TMPFILE support
- allowing AIO+DIO writes beyond EOF
- FALLOC_FL_COLLAPSE_RANGE support for fallocate syscall and XFS
implementation
- FALLOC_FL_ZERO_RANGE support for fallocate syscall and XFS
implementation
- IO verifier cleanup and rework
- stack usage reduction changes
- vm_map_ram NOIO context fixes to remove lockdep warings
- various bug fixes and cleanups
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Merge tag 'xfs-for-linus-3.15-rc1' of git://oss.sgi.com/xfs/xfs
Pull xfs update from Dave Chinner:
"There are a couple of new fallocate features in this request - it was
decided that it was easiest to push them through the XFS tree using
topic branches and have the ext4 support be based on those branches.
Hence you may see some overlap with the ext4 tree merge depending on
how they including those topic branches into their tree. Other than
that, there is O_TMPFILE support, some cleanups and bug fixes.
The main changes in the XFS tree for 3.15-rc1 are:
- O_TMPFILE support
- allowing AIO+DIO writes beyond EOF
- FALLOC_FL_COLLAPSE_RANGE support for fallocate syscall and XFS
implementation
- FALLOC_FL_ZERO_RANGE support for fallocate syscall and XFS
implementation
- IO verifier cleanup and rework
- stack usage reduction changes
- vm_map_ram NOIO context fixes to remove lockdep warings
- various bug fixes and cleanups"
* tag 'xfs-for-linus-3.15-rc1' of git://oss.sgi.com/xfs/xfs: (34 commits)
xfs: fix directory hash ordering bug
xfs: extra semi-colon breaks a condition
xfs: Add support for FALLOC_FL_ZERO_RANGE
fs: Introduce FALLOC_FL_ZERO_RANGE flag for fallocate
xfs: inode log reservations are still too small
xfs: xfs_check_page_type buffer checks need help
xfs: avoid AGI/AGF deadlock scenario for inode chunk allocation
xfs: use NOIO contexts for vm_map_ram
xfs: don't leak EFSBADCRC to userspace
xfs: fix directory inode iolock lockdep false positive
xfs: allocate xfs_da_args to reduce stack footprint
xfs: always do log forces via the workqueue
xfs: modify verifiers to differentiate CRC from other errors
xfs: print useful caller information in xfs_error_report
xfs: add xfs_verifier_error()
xfs: add helper for updating checksums on xfs_bufs
xfs: add helper for verifying checksums on xfs_bufs
xfs: Use defines for CRC offsets in all cases
xfs: skip pointless CRC updates after verifier failures
xfs: Add support FALLOC_FL_COLLAPSE_RANGE for fallocate
...
new flag in ->f_mode - FMODE_WRITER. Set by do_dentry_open() in case
when it has grabbed write access, checked by __fput() to decide whether
it wants to drop the sucker. Allows to stop bothering with mnt_clone_write()
in alloc_file(), along with fewer special_file() checks.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
