The inode operations .permission() and .getattr() use the kernfs node
write lock but all that's needed is the read lock to protect against
partial updates of these kernfs node fields which are all done under
the write lock.
And .permission() is called frequently during path walks and can cause
quite a bit of contention between kernfs node operations and path
walks when the number of concurrent walks is high.
To change kernfs_iop_getattr() and kernfs_iop_permission() to take
the rw sem read lock instead of the write lock an additional lock is
needed to protect against multiple processes concurrently updating
the inode attributes and link count in kernfs_refresh_inode().
The inode i_lock seems like the sensible thing to use to protect these
inode attribute updates so use it in kernfs_refresh_inode().
The last hunk in the patch, applied to kernfs_fill_super(), is possibly
not needed but taking the lock was present originally. I prefer to
continue to take it to protect against a partial update of the source
kernfs fields during the call to kernfs_refresh_inode() made by
kernfs_get_inode().
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Link: https://lore.kernel.org/r/162642771474.63632.16295959115893904470.stgit@web.messagingengine.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The kernfs global lock restricts the ability to perform kernfs node
lookup operations in parallel during path walks.
Change the kernfs mutex to an rwsem so that, when opportunity arises,
node searches can be done in parallel with path walk lookups.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Link: https://lore.kernel.org/r/162642770946.63632.2218304587223241374.stgit@web.messagingengine.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull vfs d_inode/d_flags memory ordering fixes from Al Viro:
"Fallout from tree-wide audit for ->d_inode/->d_flags barriers use.
Basically, the problem is that negative pinned dentries require
careful treatment - unless ->d_lock is locked or parent is held at
least shared, another thread can make them positive right under us.
Most of the uses turned out to be safe - the main surprises as far as
filesystems are concerned were
- race in dget_parent() fastpath, that might end up with the caller
observing the returned dentry _negative_, due to insufficient
barriers. It is positive in memory, but we could end up seeing the
wrong value of ->d_inode in CPU cache. Fixed.
- manual checks that result of lookup_one_len_unlocked() is positive
(and rejection of negatives). Again, insufficient barriers (we
might end up with inconsistent observed values of ->d_inode and
->d_flags). Fixed by switching to a new primitive that does the
checks itself and returns ERR_PTR(-ENOENT) instead of a negative
dentry. That way we get rid of boilerplate converting negatives
into ERR_PTR(-ENOENT) in the callers and have a single place to
deal with the barrier-related mess - inside fs/namei.c rather than
in every caller out there.
The guts of pathname resolution *do* need to be careful - the race
found by Ritesh is real, as well as several similar races.
Fortunately, it turns out that we can take care of that with fairly
local changes in there.
The tree-wide audit had not been fun, and I hate the idea of repeating
it. I think the right approach would be to annotate the places where
we are _not_ guaranteed ->d_inode/->d_flags stability and have sparse
catch regressions. But I'm still not sure what would be the least
invasive way of doing that and it's clearly the next cycle fodder"
* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fs/namei.c: fix missing barriers when checking positivity
fix dget_parent() fastpath race
new helper: lookup_positive_unlocked()
fs/namei.c: pull positivity check into follow_managed()
Most of the callers of lookup_one_len_unlocked() treat negatives are
ERR_PTR(-ENOENT). Provide a helper that would do just that. Note
that a pinned positive dentry remains positive - it's ->d_inode is
stable, etc.; a pinned _negative_ dentry can become positive at any
point as long as you are not holding its parent at least shared.
So using lookup_one_len_unlocked() needs to be careful;
lookup_positive_unlocked() is safer and that's what the callers
end up open-coding anyway.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Each kernfs_node is identified with a 64bit ID. The low 32bit is
exposed as ino and the high gen. While this already allows using inos
as keys by looking up with wildcard generation number of 0, it's
adding unnecessary complications for 64bit ino archs which can
directly use kernfs_node IDs as inos to uniquely identify each cgroup
instance.
This patch exposes IDs directly as inos on 64bit ino archs. The
conversion is mostly straight-forward.
* 32bit ino archs behave the same as before. 64bit ino archs now use
the whole 64bit ID as ino and the generation number is fixed at 1.
* 64bit inos still use the same idr allocator which gurantees that the
lower 32bits identify the current live instance uniquely and the
high 32bits are incremented whenever the low bits wrap. As the
upper 32bits are no longer used as gen and we don't wanna start ino
allocation with 33rd bit set, the initial value for highbits
allocation is changed to 0 on 64bit ino archs.
* blktrace exposes two 32bit numbers - (INO,GEN) pair - to identify
the issuing cgroup. Userland builds FILEID_INO32_GEN fids from
these numbers to look up the cgroups. To remain compatible with the
behavior, always output (LOW32,HIGH32) which will be constructed
back to the original 64bit ID by __kernfs_fh_to_dentry().
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
The current kernfs exportfs implementation uses the generic_fh_*()
helpers and FILEID_INO32_GEN[_PARENT] which limits ino to 32bits.
Let's implement custom exportfs operations and fid type to remove the
restriction.
* FILEID_KERNFS is a single u64 value whose content is
kernfs_node->id. This is the only native fid type.
* For backward compatibility with blk_log_action() path which exposes
(ino,gen) pairs which userland assembles into FILEID_INO32_GEN keys,
combine the generic keys into 64bit IDs in the same order.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
kernfs_find_and_get_node_by_ino() looks the kernfs_node matching the
specified ino. On top of that, kernfs_get_node_by_id() and
kernfs_fh_get_inode() implement full ID matching by testing the rest
of ID.
On surface, confusingly, the two are slightly different in that the
latter uses 0 gen as wildcard while the former doesn't - does it mean
that the latter can't uniquely identify inodes w/ 0 gen? In practice,
this is a distinction without a difference because generation number
starts at 1. There are no actual IDs with 0 gen, so it can always
safely used as wildcard.
Let's simplify the code by renaming kernfs_find_and_get_node_by_ino()
to kernfs_find_and_get_node_by_id(), moving all lookup logics into it,
and removing now unnecessary kernfs_get_node_by_id().
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kernfs_node->id is currently a union kernfs_node_id which represents
either a 32bit (ino, gen) pair or u64 value. I can't see much value
in the usage of the union - all that's needed is a 64bit ID which the
current code is already limited to. Using a union makes the code
unnecessarily complicated and prevents using 64bit ino without adding
practical benefits.
This patch drops union kernfs_node_id and makes kernfs_node->id a u64.
ino is stored in the lower 32bits and gen upper. Accessors -
kernfs[_id]_ino() and kernfs[_id]_gen() - are added to retrieve the
ino and gen. This simplifies ID handling less cumbersome and will
allow using 64bit inos on supported archs.
This patch doesn't make any functional changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Alexei Starovoitov <ast@kernel.org>
kernfs_find_and_get_node_by_ino() uses RCU protection. It's currently
a bit buggy because it can look up a node which hasn't been activated
yet and thus may end up exposing a node that the kernfs user is still
prepping.
While it can be fixed by pushing it further in the current direction,
it's already complicated and isn't clear whether the complexity is
justified. The main use of kernfs_find_and_get_node_by_ino() is for
exportfs operations. They aren't super hot and all the follow-up
operations (e.g. mapping to path) use normal locking anyway.
Let's switch to a dumber locking scheme and protect the lookup with
kernfs_idr_lock.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Based on 1 normalized pattern(s):
this file is released under the gplv2
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 68 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Armijn Hemel <armijn@tjaldur.nl>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190531190114.292346262@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull vfs mount infrastructure updates from Al Viro:
"The rest of core infrastructure; no new syscalls in that pile, but the
old parts are switched to new infrastructure. At that point
conversions of individual filesystems can happen independently; some
are done here (afs, cgroup, procfs, etc.), there's also a large series
outside of that pile dealing with NFS (quite a bit of option-parsing
stuff is getting used there - it's one of the most convoluted
filesystems in terms of mount-related logics), but NFS bits are the
next cycle fodder.
It got seriously simplified since the last cycle; documentation is
probably the weakest bit at the moment - I considered dropping the
commit introducing Documentation/filesystems/mount_api.txt (cutting
the size increase by quarter ;-), but decided that it would be better
to fix it up after -rc1 instead.
That pile allows to do followup work in independent branches, which
should make life much easier for the next cycle. fs/super.c size
increase is unpleasant; there's a followup series that allows to
shrink it considerably, but I decided to leave that until the next
cycle"
* 'work.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (41 commits)
afs: Use fs_context to pass parameters over automount
afs: Add fs_context support
vfs: Add some logging to the core users of the fs_context log
vfs: Implement logging through fs_context
vfs: Provide documentation for new mount API
vfs: Remove kern_mount_data()
hugetlbfs: Convert to fs_context
cpuset: Use fs_context
kernfs, sysfs, cgroup, intel_rdt: Support fs_context
cgroup: store a reference to cgroup_ns into cgroup_fs_context
cgroup1_get_tree(): separate "get cgroup_root to use" into a separate helper
cgroup_do_mount(): massage calling conventions
cgroup: stash cgroup_root reference into cgroup_fs_context
cgroup2: switch to option-by-option parsing
cgroup1: switch to option-by-option parsing
cgroup: take options parsing into ->parse_monolithic()
cgroup: fold cgroup1_mount() into cgroup1_get_tree()
cgroup: start switching to fs_context
ipc: Convert mqueue fs to fs_context
proc: Add fs_context support to procfs
...
Here is the big driver core patchset for 5.1-rc1
More patches than "normal" here this merge window, due to some work in
the driver core by Alexander Duyck to rework the async probe
functionality to work better for a number of devices, and independant
work from Rafael for the device link functionality to make it work
"correctly".
Also in here is:
- lots of BUS_ATTR() removals, the macro is about to go away
- firmware test fixups
- ihex fixups and simplification
- component additions (also includes i915 patches)
- lots of minor coding style fixups and cleanups.
All of these have been in linux-next for a while with no reported
issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core updates from Greg KH:
"Here is the big driver core patchset for 5.1-rc1
More patches than "normal" here this merge window, due to some work in
the driver core by Alexander Duyck to rework the async probe
functionality to work better for a number of devices, and independant
work from Rafael for the device link functionality to make it work
"correctly".
Also in here is:
- lots of BUS_ATTR() removals, the macro is about to go away
- firmware test fixups
- ihex fixups and simplification
- component additions (also includes i915 patches)
- lots of minor coding style fixups and cleanups.
All of these have been in linux-next for a while with no reported
issues"
* tag 'driver-core-5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (65 commits)
driver core: platform: remove misleading err_alloc label
platform: set of_node in platform_device_register_full()
firmware: hardcode the debug message for -ENOENT
driver core: Add missing description of new struct device_link field
driver core: Fix PM-runtime for links added during consumer probe
drivers/component: kerneldoc polish
async: Add cmdline option to specify drivers to be async probed
driver core: Fix possible supplier PM-usage counter imbalance
PM-runtime: Fix __pm_runtime_set_status() race with runtime resume
driver: platform: Support parsing GpioInt 0 in platform_get_irq()
selftests: firmware: fix verify_reqs() return value
Revert "selftests: firmware: remove use of non-standard diff -Z option"
Revert "selftests: firmware: add CONFIG_FW_LOADER_USER_HELPER_FALLBACK to config"
device: Fix comment for driver_data in struct device
kernfs: Allocating memory for kernfs_iattrs with kmem_cache.
sysfs: remove unused include of kernfs-internal.h
driver core: Postpone DMA tear-down until after devres release
driver core: Document limitation related to DL_FLAG_RPM_ACTIVE
PM-runtime: Take suppliers into account in __pm_runtime_set_status()
device.h: Add __cold to dev_<level> logging functions
...
Make kernfs support superblock creation/mount/remount with fs_context.
This requires that sysfs, cgroup and intel_rdt, which are built on kernfs,
be made to support fs_context also.
Notes:
(1) A kernfs_fs_context struct is created to wrap fs_context and the
kernfs mount parameters are moved in here (or are in fs_context).
(2) kernfs_mount{,_ns}() are made into kernfs_get_tree(). The extra
namespace tag parameter is passed in the context if desired
(3) kernfs_free_fs_context() is provided as a destructor for the
kernfs_fs_context struct, but for the moment it does nothing except
get called in the right places.
(4) sysfs doesn't wrap kernfs_fs_context since it has no parameters to
pass, but possibly this should be done anyway in case someone wants to
add a parameter in future.
(5) A cgroup_fs_context struct is created to wrap kernfs_fs_context and
the cgroup v1 and v2 mount parameters are all moved there.
(6) cgroup1 parameter parsing error messages are now handled by invalf(),
which allows userspace to collect them directly.
(7) cgroup1 parameter cleanup is now done in the context destructor rather
than in the mount/get_tree and remount functions.
Weirdies:
(*) cgroup_do_get_tree() calls cset_cgroup_from_root() with locks held,
but then uses the resulting pointer after dropping the locks. I'm
told this is okay and needs commenting.
(*) The cgroup refcount web. This really needs documenting.
(*) cgroup2 only has one root?
Add a suggestion from Thomas Gleixner in which the RDT enablement code is
placed into its own function.
[folded a leak fix from Andrey Vagin]
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
cc: Tejun Heo <tj@kernel.org>
cc: Li Zefan <lizefan@huawei.com>
cc: Johannes Weiner <hannes@cmpxchg.org>
cc: cgroups@vger.kernel.org
cc: fenghua.yu@intel.com
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Creating a new cache for kernfs_iattrs.
Currently, memory is allocated with kzalloc() which
always gives aligned memory. On ARM, this is 64 byte aligned.
To avoid the wastage of memory in aligning the size requested,
a new cache for kernfs_iattrs is created.
Size of struct kernfs_iattrs is 80 Bytes.
On ARM, it will come in kmalloc-128 slab.
and it will come in kmalloc-192 slab if debug info is enabled.
Extra bytes taken 48 bytes.
Total number of objects created : 4096
Total saving = 48*4096 = 192 KB
After creating new slab(When debug info is enabled) :
sh-3.2# cat /proc/slabinfo
...
kernfs_iattrs_cache 4069 4096 128 32 1 : tunables 0 0 0 : slabdata 128 128 0
...
All testing has been done on ARM target.
Signed-off-by: Ayush Mittal <ayush.m@samsung.com>
Signed-off-by: Vaneet Narang <v.narang@samsung.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
same story as with last May fixes in sysfs (7b745a4e40
"unfuck sysfs_mount()"); new_sb is left uninitialized
in case of early errors in kernfs_mount_ns() and papering
over it by treating any error from kernfs_mount_ns() as
equivalent to !new_ns ends up conflating the cases when
objects had never been transferred to a superblock with
ones when that has happened and resulting new superblock
had been dropped. Easily fixed (same way as in sysfs
case). Additionally, there's a superblock leak on
kernfs_node_dentry() failure *and* a dentry leak inside
kernfs_node_dentry() itself - the latter on probably
impossible errors, but the former not impossible to trigger
(as the matter of fact, injecting allocation failures
at that point *does* trigger it).
Cc: stable@kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The page cache and most shrinkable slab caches hold data that has been
read from disk, but there are some caches that only cache CPU work, such
as the dentry and inode caches of procfs and sysfs, as well as the subset
of radix tree nodes that track non-resident page cache.
Currently, all these are shrunk at the same rate: using DEFAULT_SEEKS for
the shrinker's seeks setting tells the reclaim algorithm that for every
two page cache pages scanned it should scan one slab object.
This is a bogus setting. A virtual inode that required no IO to create is
not twice as valuable as a page cache page; shadow cache entries with
eviction distances beyond the size of memory aren't either.
In most cases, the behavior in practice is still fine. Such virtual
caches don't tend to grow and assert themselves aggressively, and usually
get picked up before they cause problems. But there are scenarios where
that's not true.
Our database workloads suffer from two of those. For one, their file
workingset is several times bigger than available memory, which has the
kernel aggressively create shadow page cache entries for the non-resident
parts of it. The workingset code does tell the VM that most of these are
expendable, but the VM ends up balancing them 2:1 to cache pages as per
the seeks setting. This is a huge waste of memory.
These workloads also deal with tens of thousands of open files and use
/proc for introspection, which ends up growing the proc_inode_cache to
absurdly large sizes - again at the cost of valuable cache space, which
isn't a reasonable trade-off, given that proc inodes can be re-created
without involving the disk.
This patch implements a "zero-seek" setting for shrinkers that results in
a target ratio of 0:1 between their objects and IO-backed caches. This
allows such virtual caches to grow when memory is available (they do
cache/avoid CPU work after all), but effectively disables them as soon as
IO-backed objects are under pressure.
It then switches the shrinkers for procfs and sysfs metadata, as well as
excess page cache shadow nodes, to the new zero-seek setting.
Link: http://lkml.kernel.org/r/20181009184732.762-5-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Domas Mituzas <dmituzas@fb.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Rik van Riel <riel@surriel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is a pure automated search-and-replace of the internal kernel
superblock flags.
The s_flags are now called SB_*, with the names and the values for the
moment mirroring the MS_* flags that they're equivalent to.
Note how the MS_xyz flags are the ones passed to the mount system call,
while the SB_xyz flags are what we then use in sb->s_flags.
The script to do this was:
# places to look in; re security/*: it generally should *not* be
# touched (that stuff parses mount(2) arguments directly), but
# there are two places where we really deal with superblock flags.
FILES="drivers/mtd drivers/staging/lustre fs ipc mm \
include/linux/fs.h include/uapi/linux/bfs_fs.h \
security/apparmor/apparmorfs.c security/apparmor/include/lib.h"
# the list of MS_... constants
SYMS="RDONLY NOSUID NODEV NOEXEC SYNCHRONOUS REMOUNT MANDLOCK \
DIRSYNC NOATIME NODIRATIME BIND MOVE REC VERBOSE SILENT \
POSIXACL UNBINDABLE PRIVATE SLAVE SHARED RELATIME KERNMOUNT \
I_VERSION STRICTATIME LAZYTIME SUBMOUNT NOREMOTELOCK NOSEC BORN \
ACTIVE NOUSER"
SED_PROG=
for i in $SYMS; do SED_PROG="$SED_PROG -e s/MS_$i/SB_$i/g"; done
# we want files that contain at least one of MS_...,
# with fs/namespace.c and fs/pnode.c excluded.
L=$(for i in $SYMS; do git grep -w -l MS_$i $FILES; done| sort|uniq|grep -v '^fs/namespace.c'|grep -v '^fs/pnode.c')
for f in $L; do sed -i $f $SED_PROG; done
Requested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
By default we output cgroup id in blktrace. This adds an option to
display cgroup path. Since get cgroup path is a relativly heavy
operation, we don't enable it by default.
with the option enabled, blktrace will output something like this:
dd-1353 [007] d..2 293.015252: 8,0 /test/level D R 24 + 8 [dd]
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Now we have the facilities to implement exportfs operations. The idea is
cgroup can export the fhandle info to userspace, then userspace uses
fhandle to find the cgroup name. Another example is userspace can get
fhandle for a cgroup and BPF uses the fhandle to filter info for the
cgroup.
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
When working on adding exportfs operations in kernfs, I found it's hard
to initialize dentry->d_fsdata in the exportfs operations. Looks there
is no way to do it without race condition. Look at the kernfs code
closely, there is no point to set dentry->d_fsdata. inode->i_private
already points to kernfs_node, and we can get inode from a dentry. So
this patch just delete the d_fsdata usage.
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add an API to get kernfs node from inode number. We will need this to
implement exportfs operations.
This API will be used in blktrace too later, so it should be as fast as
possible. To make the API lock free, kernfs node is freed in RCU
context. And we depend on kernfs_node count/ino number to filter out
stale kernfs nodes.
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Introduce a function may_open_dev that tests MNT_NODEV and a new
superblock flab SB_I_NODEV. Use this new function in all of the
places where MNT_NODEV was previously tested.
Add the new SB_I_NODEV s_iflag to proc, sysfs, and mqueuefs as those
filesystems should never support device nodes, and a simple superblock
flags makes that very hard to get wrong. With SB_I_NODEV set if any
device nodes somehow manage to show up on on a filesystem those
device nodes will be unopenable.
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
The cgroup filesystem is in the same boat as sysfs. No one ever
permits executables of any kind on the cgroup filesystem, and there is
no reasonable future case to support executables in the future.
Therefore move the setting of SB_I_NOEXEC which makes the code proof
against future mistakes of accidentally creating executables from
sysfs to kernfs itself. Making the code simpler and covering the
sysfs, cgroup, and cgroup2 filesystems.
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Start marking filesystems with a user namespace owner, s_user_ns. In
this change this is only used for permission checks of who may mount a
filesystem. Ultimately s_user_ns will be used for translating ids and
checking capabilities for filesystems mounted from user namespaces.
The default policy for setting s_user_ns is implemented in sget(),
which arranges for s_user_ns to be set to current_user_ns() and to
ensure that the mounter of the filesystem has CAP_SYS_ADMIN in that
user_ns.
The guts of sget are split out into another function sget_userns().
The function sget_userns calls alloc_super with the specified user
namespace or it verifies the existing superblock that was found
has the expected user namespace, and fails with EBUSY when it is not.
This failing prevents users with the wrong privileges mounting a
filesystem.
The reason for the split of sget_userns from sget is that in some
cases such as mount_ns and kernfs_mount_ns a different policy for
permission checking of mounts and setting s_user_ns is necessary, and
the existence of sget_userns() allows those policies to be
implemented.
The helper mount_ns is expected to be used for filesystems such as
proc and mqueuefs which present per namespace information. The
function mount_ns is modified to call sget_userns instead of sget to
ensure the user namespace owner of the namespace whose information is
presented by the filesystem is used on the superblock.
For sysfs and cgroup the appropriate permission checks are already in
place, and kernfs_mount_ns is modified to call sget_userns so that
the init_user_ns is the only user namespace used.
For the cgroup filesystem cgroup namespace mounts are bind mounts of a
subset of the full cgroup filesystem and as such s_user_ns must be the
same for all of them as there is only a single superblock.
Mounts of sysfs that vary based on the network namespace could in principle
change s_user_ns but it keeps the analysis and implementation of kernfs
simpler if that is not supported, and at present there appear to be no
benefits from supporting a different s_user_ns on any sysfs mount.
Getting the details of setting s_user_ns correct has been
a long process. Thanks to Pavel Tikhorirorv who spotted a leak
in sget_userns. Thanks to Seth Forshee who has kept the work alive.
Thanks-to: Seth Forshee <seth.forshee@canonical.com>
Thanks-to: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Pull parallel filesystem directory handling update from Al Viro.
This is the main parallel directory work by Al that makes the vfs layer
able to do lookup and readdir in parallel within a single directory.
That's a big change, since this used to be all protected by the
directory inode mutex.
The inode mutex is replaced by an rwsem, and serialization of lookups of
a single name is done by a "in-progress" dentry marker.
The series begins with xattr cleanups, and then ends with switching
filesystems over to actually doing the readdir in parallel (switching to
the "iterate_shared()" that only takes the read lock).
A more detailed explanation of the process from Al Viro:
"The xattr work starts with some acl fixes, then switches ->getxattr to
passing inode and dentry separately. This is the point where the
things start to get tricky - that got merged into the very beginning
of the -rc3-based #work.lookups, to allow untangling the
security_d_instantiate() mess. The xattr work itself proceeds to
switch a lot of filesystems to generic_...xattr(); no complications
there.
After that initial xattr work, the series then does the following:
- untangle security_d_instantiate()
- convert a bunch of open-coded lookup_one_len_unlocked() to calls of
that thing; one such place (in overlayfs) actually yields a trivial
conflict with overlayfs fixes later in the cycle - overlayfs ended
up switching to a variant of lookup_one_len_unlocked() sans the
permission checks. I would've dropped that commit (it gets
overridden on merge from #ovl-fixes in #for-next; proper resolution
is to use the variant in mainline fs/overlayfs/super.c), but I
didn't want to rebase the damn thing - it was fairly late in the
cycle...
- some filesystems had managed to depend on lookup/lookup exclusion
for *fs-internal* data structures in a way that would break if we
relaxed the VFS exclusion. Fixing hadn't been hard, fortunately.
- core of that series - parallel lookup machinery, replacing
->i_mutex with rwsem, making lookup_slow() take it only shared. At
that point lookups happen in parallel; lookups on the same name
wait for the in-progress one to be done with that dentry.
Surprisingly little code, at that - almost all of it is in
fs/dcache.c, with fs/namei.c changes limited to lookup_slow() -
making it use the new primitive and actually switching to locking
shared.
- parallel readdir stuff - first of all, we provide the exclusion on
per-struct file basis, same as we do for read() vs lseek() for
regular files. That takes care of most of the needed exclusion in
readdir/readdir; however, these guys are trickier than lookups, so
I went for switching them one-by-one. To do that, a new method
'->iterate_shared()' is added and filesystems are switched to it
as they are either confirmed to be OK with shared lock on directory
or fixed to be OK with that. I hope to kill the original method
come next cycle (almost all in-tree filesystems are switched
already), but it's still not quite finished.
- several filesystems get switched to parallel readdir. The
interesting part here is dealing with dcache preseeding by readdir;
that needs minor adjustment to be safe with directory locked only
shared.
Most of the filesystems doing that got switched to in those
commits. Important exception: NFS. Turns out that NFS folks, with
their, er, insistence on VFS getting the fuck out of the way of the
Smart Filesystem Code That Knows How And What To Lock(tm) have
grown the locking of their own. They had their own homegrown
rwsem, with lookup/readdir/atomic_open being *writers* (sillyunlink
is the reader there). Of course, with VFS getting the fuck out of
the way, as requested, the actual smarts of the smart filesystem
code etc. had become exposed...
- do_last/lookup_open/atomic_open cleanups. As the result, open()
without O_CREAT locks the directory only shared. Including the
->atomic_open() case. Backmerge from #for-linus in the middle of
that - atomic_open() fix got brought in.
- then comes NFS switch to saner (VFS-based ;-) locking, killing the
homegrown "lookup and readdir are writers" kinda-sorta rwsem. All
exclusion for sillyunlink/lookup is done by the parallel lookups
mechanism. Exclusion between sillyunlink and rmdir is a real rwsem
now - rmdir being the writer.
Result: NFS lookups/readdirs/O_CREAT-less opens happen in parallel
now.
- the rest of the series consists of switching a lot of filesystems
to parallel readdir; in a lot of cases ->llseek() gets simplified
as well. One backmerge in there (again, #for-linus - rockridge
fix)"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (74 commits)
ext4: switch to ->iterate_shared()
hfs: switch to ->iterate_shared()
hfsplus: switch to ->iterate_shared()
hostfs: switch to ->iterate_shared()
hpfs: switch to ->iterate_shared()
hpfs: handle allocation failures in hpfs_add_pos()
gfs2: switch to ->iterate_shared()
f2fs: switch to ->iterate_shared()
afs: switch to ->iterate_shared()
befs: switch to ->iterate_shared()
befs: constify stuff a bit
isofs: switch to ->iterate_shared()
get_acorn_filename(): deobfuscate a bit
btrfs: switch to ->iterate_shared()
logfs: no need to lock directory in lseek
switch ecryptfs to ->iterate_shared
9p: switch to ->iterate_shared()
fat: switch to ->iterate_shared()
romfs, squashfs: switch to ->iterate_shared()
more trivial ->iterate_shared conversions
...
Our caller expects 0 on success, not >0.
This fixes a bug in the patch
cgroup, kernfs: make mountinfo show properly scoped path for cgroup namespaces
where /sys does not show up in mountinfo, breaking criu.
Thanks for catching this, Andrei.
Reported-by: Andrei Vagin <avagin@gmail.com>
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Patch summary:
When showing a cgroupfs entry in mountinfo, show the path of the mount
root dentry relative to the reader's cgroup namespace root.
Short explanation (courtesy of mkerrisk):
If we create a new cgroup namespace, then we want both /proc/self/cgroup
and /proc/self/mountinfo to show cgroup paths that are correctly
virtualized with respect to the cgroup mount point. Previous to this
patch, /proc/self/cgroup shows the right info, but /proc/self/mountinfo
does not.
Long version:
When a uid 0 task which is in freezer cgroup /a/b, unshares a new cgroup
namespace, and then mounts a new instance of the freezer cgroup, the new
mount will be rooted at /a/b. The root dentry field of the mountinfo
entry will show '/a/b'.
cat > /tmp/do1 << EOF
mount -t cgroup -o freezer freezer /mnt
grep freezer /proc/self/mountinfo
EOF
unshare -Gm bash /tmp/do1
> 330 160 0:34 / /sys/fs/cgroup/freezer rw,nosuid,nodev,noexec,relatime - cgroup cgroup rw,freezer
> 355 133 0:34 /a/b /mnt rw,relatime - cgroup freezer rw,freezer
The task's freezer cgroup entry in /proc/self/cgroup will simply show
'/':
grep freezer /proc/self/cgroup
9:freezer:/
If instead the same task simply bind mounts the /a/b cgroup directory,
the resulting mountinfo entry will again show /a/b for the dentry root.
However in this case the task will find its own cgroup at /mnt/a/b,
not at /mnt:
mount --bind /sys/fs/cgroup/freezer/a/b /mnt
130 25 0:34 /a/b /mnt rw,nosuid,nodev,noexec,relatime shared:21 - cgroup cgroup rw,freezer
In other words, there is no way for the task to know, based on what is
in mountinfo, which cgroup directory is its own.
Example (by mkerrisk):
First, a little script to save some typing and verbiage:
echo -e "\t/proc/self/cgroup:\t$(cat /proc/self/cgroup | grep freezer)"
cat /proc/self/mountinfo | grep freezer |
awk '{print "\tmountinfo:\t\t" $4 "\t" $5}'
Create cgroup, place this shell into the cgroup, and look at the state
of the /proc files:
2653
2653 # Our shell
14254 # cat(1)
/proc/self/cgroup: 10:freezer:/a/b
mountinfo: / /sys/fs/cgroup/freezer
Create a shell in new cgroup and mount namespaces. The act of creating
a new cgroup namespace causes the process's current cgroups directories
to become its cgroup root directories. (Here, I'm using my own version
of the "unshare" utility, which takes the same options as the util-linux
version):
Look at the state of the /proc files:
/proc/self/cgroup: 10:freezer:/
mountinfo: / /sys/fs/cgroup/freezer
The third entry in /proc/self/cgroup (the pathname of the cgroup inside
the hierarchy) is correctly virtualized w.r.t. the cgroup namespace, which
is rooted at /a/b in the outer namespace.
However, the info in /proc/self/mountinfo is not for this cgroup
namespace, since we are seeing a duplicate of the mount from the
old mount namespace, and the info there does not correspond to the
new cgroup namespace. However, trying to create a new mount still
doesn't show us the right information in mountinfo:
# propagating to other mountns
/proc/self/cgroup: 7:freezer:/
mountinfo: /a/b /mnt/freezer
The act of creating a new cgroup namespace caused the process's
current freezer directory, "/a/b", to become its cgroup freezer root
directory. In other words, the pathname directory of the directory
within the newly mounted cgroup filesystem should be "/",
but mountinfo wrongly shows us "/a/b". The consequence of this is
that the process in the cgroup namespace cannot correctly construct
the pathname of its cgroup root directory from the information in
/proc/PID/mountinfo.
With this patch, the dentry root field in mountinfo is shown relative
to the reader's cgroup namespace. So the same steps as above:
/proc/self/cgroup: 10:freezer:/a/b
mountinfo: / /sys/fs/cgroup/freezer
/proc/self/cgroup: 10:freezer:/
mountinfo: /../.. /sys/fs/cgroup/freezer
/proc/self/cgroup: 10:freezer:/
mountinfo: / /mnt/freezer
cgroup.clone_children freezer.parent_freezing freezer.state tasks
cgroup.procs freezer.self_freezing notify_on_release
3164
2653 # First shell that placed in this cgroup
3164 # Shell started by 'unshare'
14197 # cat(1)
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Tested-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time
ago with promise that one day it will be possible to implement page
cache with bigger chunks than PAGE_SIZE.
This promise never materialized. And unlikely will.
We have many places where PAGE_CACHE_SIZE assumed to be equal to
PAGE_SIZE. And it's constant source of confusion on whether
PAGE_CACHE_* or PAGE_* constant should be used in a particular case,
especially on the border between fs and mm.
Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
breakage to be doable.
Let's stop pretending that pages in page cache are special. They are
not.
The changes are pretty straight-forward:
- <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};
- page_cache_get() -> get_page();
- page_cache_release() -> put_page();
This patch contains automated changes generated with coccinelle using
script below. For some reason, coccinelle doesn't patch header files.
I've called spatch for them manually.
The only adjustment after coccinelle is revert of changes to
PAGE_CAHCE_ALIGN definition: we are going to drop it later.
There are few places in the code where coccinelle didn't reach. I'll
fix them manually in a separate patch. Comments and documentation also
will be addressed with the separate patch.
virtual patch
@@
expression E;
@@
- E << (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
expression E;
@@
- E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
@@
- PAGE_CACHE_SHIFT
+ PAGE_SHIFT
@@
@@
- PAGE_CACHE_SIZE
+ PAGE_SIZE
@@
@@
- PAGE_CACHE_MASK
+ PAGE_MASK
@@
expression E;
@@
- PAGE_CACHE_ALIGN(E)
+ PAGE_ALIGN(E)
@@
expression E;
@@
- page_cache_get(E)
+ get_page(E)
@@
expression E;
@@
- page_cache_release(E)
+ put_page(E)
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add a new kernfs api is added to lookup the dentry for a particular
kernfs path.
Signed-off-by: Aditya Kali <adityakali@google.com>
Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
hugetlbfs, kernfs and dlmfs can simply use noop_backing_dev_info instead
of creating a local duplicate.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
kernfs_pin_sb() tries to get a refcnt of the superblock.
This will be used by cgroupfs.
v2:
- make kernfs_pin_sb() return the superblock.
- drop kernfs_drop_sb().
tj: Updated the comment a bit.
[ This is a prerequisite for a bugfix. ]
Cc: <stable@vger.kernel.org> # 3.15
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
There is still one residue of sysfs remaining: the sb_magic
SYSFS_MAGIC. However this should be kernfs user specific,
so this patch moves it out. Kerrnfs user should specify their
magic number while mouting.
Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Currently, there's no way to find out which super_blocks are
associated with a given kernfs_root. Let's implement it - the planned
inotify extension to kernfs_notify() needs it.
Make kernfs_super_info point back to the super_block and chain it at
kernfs_root->supers.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
As mount() and kill_sb() is not a one-to-one match, we shoudn't get
ns refcnt unconditionally in sysfs_mount(), and instead we should
get the refcnt only when kernfs_mount() allocated a new superblock.
v2:
- Changed the name of the new argument, suggested by Tejun.
- Made the argument optional, suggested by Tejun.
v3:
- Make the new argument as second-to-last arg, suggested by Tejun.
Signed-off-by: Li Zefan <lizefan@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
---
fs/kernfs/mount.c | 8 +++++++-
fs/sysfs/mount.c | 5 +++--
include/linux/kernfs.h | 9 +++++----
3 files changed, 15 insertions(+), 7 deletions(-)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Implement helpers to determine node from dentry and root from
super_block. Also add a kernfs_rename_ns() wrapper which assumes NULL
namespace. These generally make sense and will be used by cgroup.
v2: Some dummy implementations for !CONFIG_SYSFS was missing. Fixed.
Reported by kbuild test robot.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add two super_block related syscall callbacks ->remount_fs() and
->show_options() to kernfs_syscall_ops. These simply forward the
matching super_operations.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kernfs has just been separated out from sysfs and we're already in
full conflict mode. Nothing can make the situation any worse. Let's
take the chance to name things properly.
This patch performs the following renames.
* s/sysfs_*()/kernfs_*()/ in all internal functions
* s/sysfs/kernfs/ in internal strings, comments and whatever is remaining
* Uniformly rename various vfs operations so that they're consistently
named and distinguishable.
This patch is strictly rename only and doesn't introduce any
functional difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kernfs has just been separated out from sysfs and we're already in
full conflict mode. Nothing can make the situation any worse. Let's
take the chance to name things properly.
This patch performs the following renames.
* s/sysfs_mutex/kernfs_mutex/
* s/sysfs_dentry_ops/kernfs_dops/
* s/sysfs_dir_operations/kernfs_dir_fops/
* s/sysfs_dir_inode_operations/kernfs_dir_iops/
* s/kernfs_file_operations/kernfs_file_fops/ - renamed for consistency
* s/sysfs_symlink_inode_operations/kernfs_symlink_iops/
* s/sysfs_aops/kernfs_aops/
* s/sysfs_backing_dev_info/kernfs_bdi/
* s/sysfs_inode_operations/kernfs_iops/
* s/sysfs_dir_cachep/kernfs_node_cache/
* s/sysfs_ops/kernfs_sops/
This patch is strictly rename only and doesn't introduce any
functional difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kernfs has just been separated out from sysfs and we're already in
full conflict mode. Nothing can make the situation any worse. Let's
take the chance to name things properly.
This patch performs the following renames.
* s/sysfs_open_dirent/kernfs_open_node/
* s/sysfs_open_file/kernfs_open_file/
* s/sysfs_inode_attrs/kernfs_iattrs/
* s/sysfs_addrm_cxt/kernfs_addrm_cxt/
* s/sysfs_super_info/kernfs_super_info/
* s/sysfs_info()/kernfs_info()/
* s/sysfs_open_dirent_lock/kernfs_open_node_lock/
* s/sysfs_open_file_mutex/kernfs_open_file_mutex/
* s/sysfs_of()/kernfs_of()/
This patch is strictly rename only and doesn't introduce any
functional difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kernfs has just been separated out from sysfs and we're already in
full conflict mode. Nothing can make the situation any worse. Let's
take the chance to name things properly.
This patch performs the following renames.
* s/sysfs_elem_dir/kernfs_elem_dir/
* s/sysfs_elem_symlink/kernfs_elem_symlink/
* s/sysfs_elem_attr/kernfs_elem_file/
* s/sysfs_dirent/kernfs_node/
* s/sd/kn/ in kernfs proper
* s/parent_sd/parent/
* s/target_sd/target/
* s/dir_sd/parent/
* s/to_sysfs_dirent()/rb_to_kn()/
* misc renames of local vars when they conflict with the above
Because md, mic and gpio dig into sysfs details, this patch ends up
modifying them. All are sysfs_dirent renames and trivial. While we
can avoid these by introducing a dummy wrapping struct sysfs_dirent
around kernfs_node, given the limited usage outside kernfs and sysfs
proper, I don't think such workaround is called for.
This patch is strictly rename only and doesn't introduce any
functional difference.
- mic / gpio renames were missing. Spotted by kbuild test robot.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Neil Brown <neilb@suse.de>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Ashutosh Dixit <ashutosh.dixit@intel.com>
Cc: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Move core mount code to fs/kernfs/mount.c. The respective
declarations in fs/sysfs/sysfs.h are moved to
fs/kernfs/kernfs-internal.h.
This is pure relocation.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Core sysfs implementation will be separated into kernfs so that it can
be used by other non-kobject users.
This patch creates fs/kernfs/ directory and makes boilerplate changes.
kernfs interface will be directly based on sysfs_dirent and its
forward declaration is moved to include/linux/kernfs.h which is
included from include/linux/sysfs.h. sysfs core implementation will
be gradually separated out and moved to kernfs.
This patch doesn't introduce any functional changes.
v2: mount.c added.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: linux-fsdevel@vger.kernel.org
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
