Eryu has reported that since commit 7b9ca4c61b "quota: Reduce
contention on dq_data_lock" test generic/233 occasionally fails. This is
caused by the fact that since that commit we don't generate warning and
set grace time for quota allocations that have DQUOT_SPACE_NOFAIL set
(these are for example some metadata allocations in ext4). We need these
allocations to behave regularly wrt warning generation and grace time
setting so fix the code to return to the original behavior.
Reported-and-tested-by: Eryu Guan <eguan@redhat.com>
CC: stable@vger.kernel.org
Fixes: 7b9ca4c61b
Signed-off-by: Jan Kara <jack@suse.cz>
Lock dq_dqb_lock around dquot_decr_inodes()
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Fixes: 7b9ca4c61b ("quota: Reduce contention on dq_data_lock")
Signed-off-by: Jan Kara <jack@suse.cz>
Pull quota scaling updates from Jan Kara:
"This contains changes to make the quota subsystem more scalable.
Reportedly it improves number of files created per second on ext4
filesystem on fast storage by about a factor of 2x"
* 'quota_scaling' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs: (28 commits)
quota: Add lock annotations to struct members
quota: Reduce contention on dq_data_lock
fs: Provide __inode_get_bytes()
quota: Inline dquot_[re]claim_reserved_space() into callsite
quota: Inline inode_{incr,decr}_space() into callsites
quota: Inline functions into their callsites
ext4: Disable dirty list tracking of dquots when journalling quotas
quota: Allow disabling tracking of dirty dquots in a list
quota: Remove dq_wait_unused from dquot
quota: Move locking into clear_dquot_dirty()
quota: Do not dirty bad dquots
quota: Fix possible corruption of dqi_flags
quota: Propagate ->quota_read errors from v2_read_file_info()
quota: Fix error codes in v2_read_file_info()
quota: Push dqio_sem down to ->read_file_info()
quota: Push dqio_sem down to ->write_file_info()
quota: Push dqio_sem down to ->get_next_id()
quota: Push dqio_sem down to ->release_dqblk()
quota: Remove locking for writing to the old quota format
quota: Do not acquire dqio_sem for dquot overwrites in v2 format
...
dq_data_lock is currently used to protect all modifications of quota
accounting information, consistency of quota accounting on the inode,
and dquot pointers from inode. As a result contention on the lock can be
pretty heavy.
Reduce the contention on the lock by protecting quota accounting
information by a new dquot->dq_dqb_lock and consistency of quota
accounting with inode usage by inode->i_lock.
This change reduces time to create 500000 files on ext4 on ramdisk by 50
different processes in separate directories by 6% when user quota is
turned on. When those 50 processes belong to 50 different users, the
improvement is about 9%.
Signed-off-by: Jan Kara <jack@suse.cz>
inode_incr_space() and inode_decr_space() have only two callsites.
Inline them there as that will make locking changes simpler.
Signed-off-by: Jan Kara <jack@suse.cz>
inode_add_rsv_space() and inode_sub_rsv_space() had only one callsite.
Inline them there directly. inode_claim_rsv_space() and
inode_reclaim_rsv_space() had two callsites so inline them there as
well. This will simplify further locking changes.
Signed-off-by: Jan Kara <jack@suse.cz>
Filesystems that are journalling quotas generally don't need tracking of
dirty dquots in a list since forcing a transaction commit flushes all
quotas anyway. Allow filesystem to say it doesn't want dquots to be
tracked as it reduces contention on the dq_list_lock.
Signed-off-by: Jan Kara <jack@suse.cz>
Currently every dquot carries a wait_queue_head_t used only when we are
turning quotas off to wait for last users to drop dquot references.
Since such rare case is not performance sensitive in any means, just use
a global waitqueue for this and save space in struct dquot. Also convert
the logic to use wait_event() instead of open-coding it.
Signed-off-by: Jan Kara <jack@suse.cz>
Move locking of dq_list_lock into clear_dquot_dirty(). It makes the
function more self-contained and will simplify our life later.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jan Kara <jack@suse.cz>
Currently we mark dirty even dquots that are not active (i.e.,
initialization or reading failed for them). Thus later we have to check
whether dirty dquot is really active and just clear the dirty bit if
not. Avoid this complication by just never marking non-active dquot as
dirty.
Signed-off-by: Jan Kara <jack@suse.cz>
dqi_flags modifications are protected by dq_data_lock. However the
modifications in vfs_load_quota_inode() and in mark_info_dirty() were
not which could lead to corruption of dqi_flags. Since modifications to
dqi_flags are rare, this is hard to observe in practice but in theory it
could happen. Fix the problem by always using dq_data_lock for
protection.
Signed-off-by: Jan Kara <jack@suse.cz>
Push down acquisition of dqio_sem into ->read_file_info() callback. This
is for consistency with other operations and it also allows us to get
rid of an ugliness in OCFS2.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jan Kara <jack@suse.cz>
Push down acquisition of dqio_sem into ->write_file_info() callback.
Mostly for consistency with other operations.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jan Kara <jack@suse.cz>
Push down acquisition of dqio_sem into ->get_next_id() callback. Mostly
for consistency with other operations.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jan Kara <jack@suse.cz>
Push down acquisition of dqio_sem into ->release_dqblk() callback. It
will allow quota formats to decide whether they need it or not.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jan Kara <jack@suse.cz>
Push down acquisition of dqio_sem into ->write_dqblk() callback. It will
allow quota formats to decide whether they need it or not.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jan Kara <jack@suse.cz>
Push down acquisition of dqio_sem into ->read_dqblk() callback. It will
allow quota formats to decide whether they need it or not.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jan Kara <jack@suse.cz>
Currently dquot writeout is only protected by dqio_sem held for writing.
As we transition to a finer grained locking we will use dquot->dq_lock
instead. So acquire it in dquot_commit() and move dqio_sem just around
->commit_dqblk() call as it is still needed to serialize quota file
changes.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jan Kara <jack@suse.cz>
vfs_load_quota_inode() needs dqio_sem only for reading. In fact dqio_sem
is not needed there at all since the function can be called only during
quota on when quota file cannot be modified but let's leave the
protection there since it is logical and the path is in no way
performance critical.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jan Kara <jack@suse.cz>
dquot_get_next_id() needs dqio_sem only for reading to protect against
racing with modification of quota file structure.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jan Kara <jack@suse.cz>
We need dqio_sem held just for reading when calling ->read_dqblk() in
dquot_acquire(). Also dqio_sem is not needed when setting DQ_READ_B and
DQ_ACTIVE_B as concurrent reads and dquot activations are serialized by
dq_lock. So acquire and release dqio_sem closer to the place where it is
needed. This reduces lock hold time and will make locking changes
easier.
Signed-off-by: Jan Kara <jack@suse.cz>
Currently we compare total space (curspace + rsvspace)
with space limit in quota-tools when setting grace time
and also in check_bdq(), but we missing rsvspace in
somewhere else, correct them. This patch also fix incorrect
zero dqb_btime and grace time updating failure when we use
rsvspace(e.g. ext4 dalloc feature).
Signed-off-by: zhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Ext4 ea_inode feature allows storing xattr values in external inodes to
be able to store values that are bigger than a block in size. Ext4 also
has deduplication support for these type of inodes. With deduplication,
the actual storage waste is eliminated but the users of such inodes are
still charged full quota for the inodes as if there was no sharing
happening in the background.
This design requires ext4 to manually charge the users because the
inodes are shared.
An implication of this is that, if someone calls chown on a file that
has such references we need to transfer the quota for the file and xattr
inodes. Current dquot_transfer() function implicitly transfers one inode
charge. With ea_inode feature, we would like to transfer multiple inode
charges.
Add get_inode_usage callback which can interrogate the total number of
inodes that were charged for a given inode.
[ Applied fix from Colin King to make sure the 'ret' variable is
initialized on the successful return path. Detected by
CoverityScan, CID#1446616 ("Uninitialized scalar variable") --tytso]
Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Jan Kara <jack@suse.cz>
ext4_xattr_block_set() calls dquot_alloc_block() to charge for an xattr
block when new references are made. However if dquot_initialize() hasn't
been called on an inode, request for charging is effectively ignored
because ext4_inode_info->i_dquot is not initialized yet.
Add dquot_initialize() to call paths that lead to ext4_xattr_block_set().
Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Currently we set IMMUTABLE and NOATIME flags on quota files to stop
userspace from messing with them. Now that all filesystems set these
flags in their quota_on handlers, we can stop setting the flags in
generic quota code. This will allow filesystems to stop copying i_flags
to their on-disk flags on various occasions.
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Jan Kara <jack@suse.cz>
Add #include <linux/cred.h> dependencies to all .c files rely on sched.h
doing that for them.
Note that even if the count where we need to add extra headers seems high,
it's still a net win, because <linux/sched.h> is included in over
2,200 files ...
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull quota, fsnotify and ext2 updates from Jan Kara:
"Changes to locking of some quota operations from dedicated quota mutex
to s_umount semaphore, a fsnotify fix and a simple ext2 fix"
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
quota: Fix bogus warning in dquot_disable()
fsnotify: Fix possible use-after-free in inode iteration on umount
ext2: reject inodes with negative size
quota: Remove dqonoff_mutex
ocfs2: Use s_umount for quota recovery protection
quota: Remove dqonoff_mutex from dquot_scan_active()
ocfs2: Protect periodic quota syncing with s_umount semaphore
quota: Use s_umount protection for quota operations
quota: Hold s_umount in exclusive mode when enabling / disabling quotas
fs: Provide function to get superblock with exclusive s_umount
dquot_disable() was warning when sb_has_quota_loaded() was true when
invalidating page cache for quota files. The thinking behind this
warning was that we must have raced with somebody else turning quotas on
and this should not happen because all places modifying quota state must
hold s_umount exclusively now. However sb_has_quota_loaded() can be also
true at this point when we are just suspending quotas on remount
read-only. Just restore the behavior to situation before commit
c3b004460d ("quota: Remove dqonoff_mutex") which introduced the
warning.
The code in dquot_disable() can be further simplified with the new
locking of quota state changes however let's leave that to a separate
commit that can get more testing exposure.
Fixes: c3b004460d
Signed-off-by: Jan Kara <jack@suse.cz>
The only places that were grabbing dqonoff_mutex are functions turning
quotas on and off and these are properly serialized using s_umount
semaphore. Remove dqonoff_mutex.
Signed-off-by: Jan Kara <jack@suse.cz>
All callers of dquot_scan_active() now hold s_umount so we can rely on
that lock to protect us against quota state changes.
Signed-off-by: Jan Kara <jack@suse.cz>
Writeback quota is protected by s_umount semaphore held for reading
because every writeback must be protected by that lock (grabbed either
by the generic writeback code or by quotactl handler). Getting next
available ID in quota file, querying quota state, setting quota
information, getting quota format are all quotactl operations protected
by s_umount semaphore held for reading grabbed in quotactl handler.
This also fixes lockdep splat about possible deadlock during filesystem
freezing where sync_filesystem() is called with page-faults already
blocked but sync_filesystem() calls into dquot_writeback_dquots() which
grabs dqonoff_mutex which ranks above i_mutex (vfs_load_quota_inode()
grabs i_mutex under dqonoff_mutex) which clearly ranks below page fault
freeze protection (e.g. via mmap_sem dependencies). The reported problem
is not a real deadlock possibility since during quota on we check
whether filesystem freezing is not in progress but still it is good to
have this fixed.
Reported-by: Ted Tso <tytso@mit.edu>
Reported-by: Eric Whitney <enwlinux@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Currently we hold s_umount semaphore only in shared mode when enabling
or disabling quotas and use dqonoff_mutex for serializing quota state
changes on a filesystem and also quota state changes with other places
depending on current quota state. Using dedicated mutex for this causes
possible deadlocks during filesystem freezing (see following commit for
details) so we transition to using s_umount semaphore for the necessary
synchronization whose lock ordering is properly handled by the
filesystem freezing code. As a start grab s_umount in exclusive mode
when enabling / disabling quotas.
Signed-off-by: Jan Kara <jack@suse.cz>
Pull userns vfs updates from Eric Biederman:
"This tree contains some very long awaited work on generalizing the
user namespace support for mounting filesystems to include filesystems
with a backing store. The real world target is fuse but the goal is
to update the vfs to allow any filesystem to be supported. This
patchset is based on a lot of code review and testing to approach that
goal.
While looking at what is needed to support the fuse filesystem it
became clear that there were things like xattrs for security modules
that needed special treatment. That the resolution of those concerns
would not be fuse specific. That sorting out these general issues
made most sense at the generic level, where the right people could be
drawn into the conversation, and the issues could be solved for
everyone.
At a high level what this patchset does a couple of simple things:
- Add a user namespace owner (s_user_ns) to struct super_block.
- Teach the vfs to handle filesystem uids and gids not mapping into
to kuids and kgids and being reported as INVALID_UID and
INVALID_GID in vfs data structures.
By assigning a user namespace owner filesystems that are mounted with
only user namespace privilege can be detected. This allows security
modules and the like to know which mounts may not be trusted. This
also allows the set of uids and gids that are communicated to the
filesystem to be capped at the set of kuids and kgids that are in the
owning user namespace of the filesystem.
One of the crazier corner casees this handles is the case of inodes
whose i_uid or i_gid are not mapped into the vfs. Most of the code
simply doesn't care but it is easy to confuse the inode writeback path
so no operation that could cause an inode write-back is permitted for
such inodes (aka only reads are allowed).
This set of changes starts out by cleaning up the code paths involved
in user namespace permirted mounts. Then when things are clean enough
adds code that cleanly sets s_user_ns. Then additional restrictions
are added that are possible now that the filesystem superblock
contains owner information.
These changes should not affect anyone in practice, but there are some
parts of these restrictions that are changes in behavior.
- Andy's restriction on suid executables that does not honor the
suid bit when the path is from another mount namespace (think
/proc/[pid]/fd/) or when the filesystem was mounted by a less
privileged user.
- The replacement of the user namespace implicit setting of MNT_NODEV
with implicitly setting SB_I_NODEV on the filesystem superblock
instead.
Using SB_I_NODEV is a stronger form that happens to make this state
user invisible. The user visibility can be managed but it caused
problems when it was introduced from applications reasonably
expecting mount flags to be what they were set to.
There is a little bit of work remaining before it is safe to support
mounting filesystems with backing store in user namespaces, beyond
what is in this set of changes.
- Verifying the mounter has permission to read/write the block device
during mount.
- Teaching the integrity modules IMA and EVM to handle filesystems
mounted with only user namespace root and to reduce trust in their
security xattrs accordingly.
- Capturing the mounters credentials and using that for permission
checks in d_automount and the like. (Given that overlayfs already
does this, and we need the work in d_automount it make sense to
generalize this case).
Furthermore there are a few changes that are on the wishlist:
- Get all filesystems supporting posix acls using the generic posix
acls so that posix_acl_fix_xattr_from_user and
posix_acl_fix_xattr_to_user may be removed. [Maintainability]
- Reducing the permission checks in places such as remount to allow
the superblock owner to perform them.
- Allowing the superblock owner to chown files with unmapped uids and
gids to something that is mapped so the files may be treated
normally.
I am not considering even obvious relaxations of permission checks
until it is clear there are no more corner cases that need to be
locked down and handled generically.
Many thanks to Seth Forshee who kept this code alive, and putting up
with me rewriting substantial portions of what he did to handle more
corner cases, and for his diligent testing and reviewing of my
changes"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (30 commits)
fs: Call d_automount with the filesystems creds
fs: Update i_[ug]id_(read|write) to translate relative to s_user_ns
evm: Translate user/group ids relative to s_user_ns when computing HMAC
dquot: For now explicitly don't support filesystems outside of init_user_ns
quota: Handle quota data stored in s_user_ns in quota_setxquota
quota: Ensure qids map to the filesystem
vfs: Don't create inodes with a uid or gid unknown to the vfs
vfs: Don't modify inodes with a uid or gid unknown to the vfs
cred: Reject inodes with invalid ids in set_create_file_as()
fs: Check for invalid i_uid in may_follow_link()
vfs: Verify acls are valid within superblock's s_user_ns.
userns: Handle -1 in k[ug]id_has_mapping when !CONFIG_USER_NS
fs: Refuse uid/gid changes which don't map into s_user_ns
selinux: Add support for unprivileged mounts from user namespaces
Smack: Handle labels consistently in untrusted mounts
Smack: Add support for unprivileged mounts from user namespaces
fs: Treat foreign mounts as nosuid
fs: Limit file caps to the user namespace of the super block
userns: Remove the now unnecessary FS_USERNS_DEV_MOUNT flag
userns: Remove implicit MNT_NODEV fragility.
...
Mostly supporting filesystems outside of init_user_ns is
s/&init_usre_ns/dquot->dq_sb->s_user_ns/. An actual need for
supporting quotas on filesystems outside of s_user_ns is quite a ways
away and to be done responsibily needs an audit on what can happen
with hostile quota files. Until that audit is complete don't attempt
to support quota files on filesystems outside of s_user_ns.
Cc: Jan Kara <jack@suse.cz>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Introduce the helper qid_has_mapping and use it to ensure that the
quota system only considers qids that map to the filesystems
s_user_ns.
In practice for quota supporting filesystems today this is the exact
same check as qid_valid. As only 0xffffffff aka (qid_t)-1 does not
map into init_user_ns.
Replace the qid_valid calls with qid_has_mapping as values come in
from userspace. This is harmless today and it prepares the quota
system to work on filesystems with quotas but mounted by unprivileged
users.
Call qid_has_mapping from dqget. This ensures the passed in qid has a
prepresentation on the underlying filesystem. Previously this was
unnecessary as filesystesm never had qids that could not map. With
the introduction of filesystems outside of s_user_ns this will not
remain true.
All of this ensures the quota code never has to deal with qids that
don't map to the underlying filesystem.
Cc: Jan Kara <jack@suse.cz>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
The quota subsystem has two formats, the old v1 format using architecture
specific time_t values on the on-disk format, while the v2 format
(introduced in Linux 2.5.16 and 2.4.22) uses fixed 64-bit little-endian.
While there is no future for the v1 format beyond y2038, the v2 format
is almost there on 32-bit architectures, as both the user interface
and the on-disk format use 64-bit timestamps, just not the time_t
inbetween.
This changes the internal representation to use time64_t, which will
end up doing the right thing everywhere for v2 format.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Currently we oopsed when Q_GETNEXTQUOTA got called when quota was
disabled. Properly check whether quota is enabled for the filesystem
before calling into quota format handler.
Reported-by: Ted Tso <tytso@mit.edu>
Signed-off-by: Jan Kara <jack@suse.cz>
Pull UDF and quota updates from Jan Kara:
"This contains a rewrite of UDF handling of filename encoding to fix
remaining overflow issues from Andrew Gabbasov and quota changes to
support new Q_[X]GETNEXTQUOTA quotactl for VFS quota formats"
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
quota: Fix possible GPF due to uninitialised pointers
ext4: Make Q_GETNEXTQUOTA work for quota in hidden inodes
quota: Forbid Q_GETQUOTA and Q_GETNEXTQUOTA for frozen filesystem
quota: Fix possible races during quota loading
ocfs2: Implement get_next_id()
quota_v2: Implement get_next_id() for V2 quota format
quota: Add support for ->get_nextdqblk() for VFS quota
udf: Merge linux specific translation into CS0 conversion function
udf: Remove struct ustr as non-needed intermediate storage
udf: Use separate buffer for copying split names
udf: Adjust UDF_NAME_LEN to better reflect actual restrictions
udf: Join functions for UTF8 and NLS conversions
udf: Parameterize output length in udf_put_filename
quota: Allow Q_GETQUOTA for frozen filesystem
quota: Fixup comments about return value of Q_[X]GETNEXTQUOTA
When dqget() in __dquot_initialize() fails e.g. due to IO error,
__dquot_initialize() will pass an array of uninitialized pointers to
dqput_all() and thus can lead to deference of random data. Fix the
problem by properly initializing the array.
CC: stable@vger.kernel.org
Signed-off-by: Nikolay Borisov <kernel@kyup.com>
Signed-off-by: Jan Kara <jack@suse.cz>
When loading new quota structure from disk, there is a possibility caller
of dqget() will see uninitialized data due to CPU reordering loads or
stores - loads from dquot can be reordered before test of DQ_ACTIVE_B
bit or setting of this bit could be reordered before filling of the
structure. Fix the issue by adding proper memory barriers.
Signed-off-by: Jan Kara <jack@suse.cz>
Add infrastructure for supporting get_nextdqblk() callback for VFS
quotas. Translate the operation into a callback to appropriate
filesystem and consequently to quota format callback.
Signed-off-by: Jan Kara <jack@suse.cz>
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>
The Kconfig currently controlling compilation of this code is:
config QUOTA
bool "Quota support"
...meaning that it currently is not being built as a module by anyone.
Lets remove the couple traces of modularity so that when reading the
driver there is no doubt it is builtin-only.
Since module_init translates to device_initcall in the non-modular
case, the init ordering gets bumped to one level earlier when we
use the more appropriate fs_initcall here. However we've made similar
changes before without any fallout and none is expected here either.
We don't delete module.h because the code in turn tries to load other
modules as appropriate and so it still needs that header.
Cc: Jan Kara <jack@suse.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Pull vfs updates from Al Viro:
"In this one:
- d_move fixes (Eric Biederman)
- UFS fixes (me; locking is mostly sane now, a bunch of bugs in error
handling ought to be fixed)
- switch of sb_writers to percpu rwsem (Oleg Nesterov)
- superblock scalability (Josef Bacik and Dave Chinner)
- swapon(2) race fix (Hugh Dickins)"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (65 commits)
vfs: Test for and handle paths that are unreachable from their mnt_root
dcache: Reduce the scope of i_lock in d_splice_alias
dcache: Handle escaped paths in prepend_path
mm: fix potential data race in SyS_swapon
inode: don't softlockup when evicting inodes
inode: rename i_wb_list to i_io_list
sync: serialise per-superblock sync operations
inode: convert inode_sb_list_lock to per-sb
inode: add hlist_fake to avoid the inode hash lock in evict
writeback: plug writeback at a high level
change sb_writers to use percpu_rw_semaphore
shift percpu_counter_destroy() into destroy_super_work()
percpu-rwsem: kill CONFIG_PERCPU_RWSEM
percpu-rwsem: introduce percpu_rwsem_release() and percpu_rwsem_acquire()
percpu-rwsem: introduce percpu_down_read_trylock()
document rwsem_release() in sb_wait_write()
fix the broken lockdep logic in __sb_start_write()
introduce __sb_writers_{acquired,release}() helpers
ufs_inode_get{frag,block}(): get rid of 'phys' argument
ufs_getfrag_block(): tidy up a bit
...
The process of reducing contention on per-superblock inode lists
starts with moving the locking to match the per-superblock inode
list. This takes the global lock out of the picture and reduces the
contention problems to within a single filesystem. This doesn't get
rid of contention as the locks still have global CPU scope, but it
does isolate operations on different superblocks form each other.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Dave Chinner <dchinner@redhat.com>
