Commit Graph

25002 Commits

Author SHA1 Message Date
Al Viro
c71053659e vfs: spread struct mount - __lookup_mnt() result
switch __lookup_mnt() to returning struct mount *; callers adjusted.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:56:58 -05:00
Al Viro
7d6fec45a5 vfs: start hiding vfsmount guts series
Almost all fields of struct vfsmount are used only by core VFS (and
a fairly small part of it, at that).  The plan: embed struct vfsmount
into struct mount, making the latter visible only to core parts of VFS.
Then move fields from vfsmount to mount, eventually leaving only
mnt_root/mnt_sb/mnt_flags in struct vfsmount.  Filesystem code still
gets pointers to struct vfsmount and remains unchanged; all such
pointers go to struct vfsmount embedded into the instances of struct
mount allocated by fs/namespace.c.  When fs/namespace.c et.al. get
a pointer to vfsmount, they turn it into pointer to mount (using
container_of) and work with that.

This is the first part of series; struct mount is introduced,
allocation switched to using it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:56:57 -05:00
Al Viro
dabe0dc194 vfs: fix the rest of sget() races
unfortunately, just checking MS_BORN after having grabbed ->s_umount in
sget() is not enough; places that pick superblock from a list and
grab s_umount shared need the same check in addition to checking for
->s_root; otherwise three-way race between failing mount, sget() and
such list-walker can leave us with list-walker coming *second*, when
temporary active ref grabbed by sget() (to be dropped when sget()
notices that original mount has failed by checking MS_BORN) has
lead to deactivate_locked_super() from failing ->mount() *not* doing
->kill_sb() and just releasing ->s_umount.  Once sget() gets through
and notices that MS_BORN had never been set it will drop the active
ref and fs will be shut down and kicked out of all lists, but it's
too late for something like sync_supers().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:53:10 -05:00
Al Viro
cf31e70d6c vfs: new helper - vfs_ustat()
... and bury user_get_super()/statfs_by_dentry() - they are
purely internal now.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:53:07 -05:00
Al Viro
c972b4bc83 vfs: live vfsmounts never have NULL ->mnt_sb
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:52:42 -05:00
Al Viro
4c1d5a64f1 vfs: for usbfs, etc. internal vfsmounts ->mnt_sb->s_root == ->mnt_root
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:52:41 -05:00
Al Viro
84b92d39f9 vfs: pipe.c is really non-modular
... so no exitcalls there.  Not much would work if pipe(2) would stop
working, after all...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:52:41 -05:00
Al Viro
6b520e0565 vfs: fix the stupidity with i_dentry in inode destructors
Seeing that just about every destructor got that INIT_LIST_HEAD() copied into
it, there is no point whatsoever keeping this INIT_LIST_HEAD in inode_init_once();
the cost of taking it into inode_init_always() will be negligible for pipes
and sockets and negative for everything else.  Not to mention the removal of
boilerplate code from ->destroy_inode() instances...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:52:40 -05:00
Al Viro
2a79f17e4a vfs: mnt_drop_write_file()
new helper (wrapper around mnt_drop_write()) to be used in pair with
mnt_want_write_file().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:52:40 -05:00
Al Viro
8c9379e972 constify seq_file stuff
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:52:40 -05:00
Al Viro
79e801a906 vfs: make do_kern_mount() static
the only user outside of fs/namespace.c has died

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:52:39 -05:00
Al Viro
a5166169f9 vfs: convert fs_supers to hlist
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:52:39 -05:00
Al Viro
5352d3b65a make nfs_follow_remote_path() handle ERR_PTR() passed as root_mnt
... rather than duplicating that in callers

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:52:39 -05:00
Al Viro
5ffc2836a2 vfs: kill ->mnt_devname use in afs printks
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:52:38 -05:00
Al Viro
e407699ef5 btrfs, nfs, apparmor: don't pull mnt_namespace.h for no reason...
it's not needed anymore; we used to, back when we had to do
mount_subtree() by hand, complete with put_mnt_ns() in it.
No more...  Apparmor didn't need it since the __d_path() fix.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:52:38 -05:00
Al Viro
aa0a4cf0ab vfs: dentry_reset_mounted() doesn't use vfsmount argument
lose it

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:52:37 -05:00
Al Viro
6c449c8dfe unexport put_mnt_ns(), make create_mnt_ns() static outright
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:52:37 -05:00
Al Viro
aafd08dad0 vfs: add missing parens in pnode.h macros
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:52:37 -05:00
Al Viro
afac7cba7e vfs: more mnt_parent cleanups
a) mount --move is checking that ->mnt_parent is non-NULL before
looking if that parent happens to be shared; ->mnt_parent is never
NULL and it's not even an misspelled !mnt_has_parent()

b) pivot_root open-codes is_path_reachable(), poorly.

c) so does path_is_under(), while we are at it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:52:36 -05:00
Al Viro
b2dba1af3c vfs: new internal helper: mnt_has_parent(mnt)
vfsmounts have ->mnt_parent pointing either to a different vfsmount
or to itself; it's never NULL and termination condition in loops
traversing the tree towards root is mnt == mnt->mnt_parent.  At least
one place (see the next patch) is confused about what's going on;
let's add an explicit helper checking it right way and use it in
all places where we need it.  Not that there had been too many,
but...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:52:36 -05:00
Al Viro
aa9c0e07bb vfs: kill pointless helpers in namespace.c
mnt_{inc,dec}_count() is not cleaner than doing the corresponding
mnt_add_count() directly and mnt_set_count() is not used at all.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:52:36 -05:00
Al Viro
bad0dcffc2 new helpers: fh_{want,drop}_write()
A bunch of places in nfsd does mnt_{want,drop}_write on vfsmount of
export of given fhandle.  Switched to obvious inlined helpers...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:52:35 -05:00
Al Viro
a561be7100 switch a bunch of places to mnt_want_write_file()
it's both faster (in case when file has been opened for write) and cleaner.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:52:35 -05:00
Al Viro
f47ec3f283 trim fs/internal.h
some stuff in there can actually become static; some belongs to pnode.h
as it's a private interface between namespace.c and pnode.c...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:52:35 -05:00
Al Viro
5ede7b1cfa pull manipulations of rpc_cred inside alloc_nfs_open_context()
No need to duplicate them in both callers; make it return
ERR_PTR(-ENOMEM) on allocation failure instead of NULL and
it'll be able to report rpc_lookup_cred() failures just
fine.  Callers are much happier that way...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03 22:52:34 -05:00
Linus Torvalds
d65616a92c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
  ceph: disable use of dcache for readdir etc.
2011-12-30 13:34:22 -08:00
Linus Torvalds
d2bac6ab93 Merge branch 'for-linus' of git://oss.sgi.com/xfs/xfs
* 'for-linus' of git://oss.sgi.com/xfs/xfs:
  xfs: log all dirty inodes in xfs_fs_sync_fs
  xfs: log the inode in ->write_inode calls for kupdate
2011-12-29 17:05:45 -08:00
Andreas Schwab
34845636a1 procfs: do not confuse jiffies with cputime64_t
Commit 2a95ea6c0d ("procfs: do not overflow get_{idle,iowait}_time
for nohz") did not take into account that one some architectures jiffies
and cputime use different units.

This causes get_idle_time() to return numbers in the wrong units, making
the idle time fields in /proc/stat wrong.

Instead of converting the usec value returned by
get_cpu_{idle,iowait}_time_us to units of jiffies, use the new function
usecs_to_cputime64 to convert it to the correct unit of cputime64_t.

Signed-off-by: Andreas Schwab <schwab@linux-m68k.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "Artem S. Tashkinov" <t.artem@mailcity.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-12-29 16:31:57 -08:00
Sage Weil
a4d46363ce ceph: disable use of dcache for readdir etc.
Ceph attempts to use the dcache to satisfy negative lookups and readdir
when the entire directory contents are in cache.  Disable this behavior
until lingering bugs in this code are shaken out; we'll re-enable these
hooks once things are fully stable.

Signed-off-by: Sage Weil <sage@newdream.net>
2011-12-29 08:05:14 -08:00
Linus Torvalds
6d4b9e38d3 vfs: fix handling of lock allocation failure in lease-break case
Bruce Fields notes that commit 778fc546f7 ("locks: fix tracking of
inprogress lease breaks") introduced a possible error pointer
dereference on failure to allocate memory.  locks_conflict() will
dereference the passed-in new lease lock structure that may be an error pointer.

This means an open (without O_NONBLOCK set) on a file with a lease
applied (generally only done when Samba or nfsd (with v4) is running)
could crash if a kmalloc() fails.

So instead of playing games with IS_ERROR() all over the place, just
check the allocation failure early.  That makes the code more
straightforward, and avoids this possible bad pointer dereference.

Based-on-patch-by: J. Bruce Fields <bfields@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-12-26 10:25:26 -08:00
Linus Torvalds
6d451c578c for linus: writeback reason binary tracing format fix
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Merge tag 'writeback' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux

for linus: writeback reason binary tracing format fix

* tag 'writeback' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux:
  writeback: show writeback reason with __print_symbolic
2011-12-23 20:25:36 -08:00
Linus Torvalds
827fa4c762 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  Btrfs: call d_instantiate after all ops are setup
  Btrfs: fix worker lock misuse in find_worker
2011-12-23 14:58:39 -08:00
Christoph Hellwig
be4f1ac828 xfs: log all dirty inodes in xfs_fs_sync_fs
Since Linux 2.6.36 the writeback code has introduces various measures for
live lock prevention during sync().  Unfortunately some of these are
actively harmful for the XFS model, where the inode gets marked dirty for
metadata from the data I/O handler.

The older_than_this checks that are now more strictly enforced since

    writeback: avoid livelocking WB_SYNC_ALL writeback

by only calling into __writeback_inodes_sb and thus only sampling the
current cut off time once.  But on a slow enough devices the previous
asynchronous sync pass might not have fully completed yet, and thus XFS
might mark metadata dirty only after that sampling of the cut off time for
the blocking pass already happened.  I have not myself reproduced this
myself on a real system, but by introducing artificial delay into the
XFS I/O completion workqueues it can be reproduced easily.

Fix this by iterating over all XFS inodes in ->sync_fs and log all that
are dirty.  This might log inode that only got redirtied after the
previous pass, but given how cheap delayed logging of inodes is it
isn't a major concern for performance.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Tested-by: Mark Tinguely <tinguely@sgi.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
2011-12-23 16:41:47 -06:00
Christoph Hellwig
0b8fd3033c xfs: log the inode in ->write_inode calls for kupdate
If the writeback code writes back an inode because it has expired we currently
use the non-blockin ->write_inode path.  This means any inode that is pinned
is skipped.  With delayed logging and a workload that has very little log
traffic otherwise it is very likely that an inode that gets constantly
written to is always pinned, and thus we keep refusing to write it.  The VM
writeback code at that point redirties it and doesn't try to write it again
for another 30 seconds.  This means under certain scenarious time based
metadata writeback never happens.

Fix this by calling into xfs_log_inode for kupdate in addition to data
integrity syncs, and thus transfer the inode to the log ASAP.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Tested-by: Mark Tinguely <tinguely@sgi.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
2011-12-23 16:41:47 -06:00
Al Viro
08c422c27f Btrfs: call d_instantiate after all ops are setup
This closes races where btrfs is calling d_instantiate too soon during
inode creation.  All of the callers of btrfs_add_nondir are updated to
instantiate after the inode is fully setup in memory.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2011-12-23 08:02:26 -05:00
Chris Mason
8d532b2afb Btrfs: fix worker lock misuse in find_worker
Dan Carpenter noticed that we were doing a double unlock on the worker
lock, and sometimes picking a worker thread without the lock held.

This fixes both errors.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
2011-12-23 07:53:00 -05:00
Linus Torvalds
822a5d3131 Merge branch 'bugfixes' of git://git.linux-nfs.org/projects/trondmy/linux-nfs
* 'bugfixes' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  NFS: Fix a regression in nfs_file_llseek()
  NFSv4: Do not accept delegated opens when a delegation recall is in effect
  NFSv4: Ensure correct locking when accessing the 'lock_states' list
  NFSv4.1: Ensure that we handle _all_ SEQUENCE status bits.
  NFSv4: Don't error if we handled it in nfs4_recovery_handle_error
  SUNRPC: Ensure we always bump the backlog queue in xprt_free_slot
  SUNRPC: Fix the execution time statistics in the face of RPC restarts
2011-12-20 11:31:56 -08:00
Haogang Chen
481fe17e97 nilfs2: potential integer overflow in nilfs_ioctl_clean_segments()
There is a potential integer overflow in nilfs_ioctl_clean_segments().
When a large argv[n].v_nmembs is passed from the userspace, the subsequent
call to vmalloc() will allocate a buffer smaller than expected, which
leads to out-of-bound access in nilfs_ioctl_move_blocks() and
lfs_clean_segments().

The following check does not prevent the overflow because nsegs is also
controlled by the userspace and could be very large.

		if (argv[n].v_nmembs > nsegs * nilfs->ns_blocks_per_segment)
			goto out_free;

This patch clamps argv[n].v_nmembs to UINT_MAX / argv[n].v_size, and
returns -EINVAL when overflow.

Signed-off-by: Haogang Chen <haogangchen@gmail.com>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-12-20 10:25:04 -08:00
Thomas Meyer
695c60f21c nilfs2: unbreak compat ioctl
commit 828b1c50ae ("nilfs2: add compat ioctl") incidentally broke all
other NILFS compat ioctls.  Make them work again.

Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Tested-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: <stable@vger.kernel.org> [3.0+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-12-20 10:25:04 -08:00
Wu Fengguang
b3bba872dd writeback: show writeback reason with __print_symbolic
This makes the binary trace understandable by trace-cmd.

CC: Dave Chinner <david@fromorbit.com>
CC: Curt Wohlgemuth <curtw@google.com>
CC: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
2011-12-18 14:20:17 +08:00
Linus Torvalds
c9a7fe9672 Merge branches 'for-linus' and 'for-linus-3.2' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  Btrfs: unplug every once and a while
  Btrfs: deal with NULL srv_rsv in the delalloc inode reservation code
  Btrfs: only set cache_generation if we setup the block group
  Btrfs: don't panic if orphan item already exists
  Btrfs: fix leaked space in truncate
  Btrfs: fix how we do delalloc reservations and how we free reservations on error
  Btrfs: deal with enospc from dirtying inodes properly
  Btrfs: fix num_workers_starting bug and other bugs in async thread
  BTRFS: Establish i_ops before calling d_instantiate
  Btrfs: add a cond_resched() into the worker loop
  Btrfs: fix ctime update of on-disk inode
  btrfs: keep orphans for subvolume deletion
  Btrfs: fix inaccurate available space on raid0 profile
  Btrfs: fix wrong disk space information of the files
  Btrfs: fix wrong i_size when truncating a file to a larger size
  Btrfs: fix btrfs_end_bio to deal with write errors to a single mirror

* 'for-linus-3.2' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  btrfs: lower the dirty balance poll interval
2011-12-16 12:15:50 -08:00
Wu Fengguang
142349f541 btrfs: lower the dirty balance poll interval
Tests show that the original large intervals can easily make the dirty
limit exceeded on 100 concurrent dd's. So adapt to as large as the
next check point selected by the dirty throttling algorithm.

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
2011-12-16 12:32:57 -05:00
Trond Myklebust
6c52961743 NFS: Fix a regression in nfs_file_llseek()
After commit 06222e491e (fs: handle
SEEK_HOLE/SEEK_DATA properly in all fs's that define their own llseek)
the behaviour of llseek() was changed so that it always revalidates
the file size. The bug appears to be due to a logic error in the
afore-mentioned commit, which always evaluates to 'true'.

Reported-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@vger.kernel.org [>=3.1]
2011-12-15 18:44:36 -05:00
Chris Mason
d85c8a6f1b Btrfs: unplug every once and a while
The btrfs io submission threads can build up massive plug lists.  This
keeps things more reasonable so we don't hand over huge dumps of IO at
once.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2011-12-15 15:38:41 -05:00
Chris Mason
567a45e917 Merge branch 'for-chris' of http://git.kernel.org/pub/scm/linux/kernel/git/josef/btrfs-work into integration
Conflicts:
	fs/btrfs/inode.c

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2011-12-15 13:43:49 -05:00
Chris Mason
e755d9ab38 Btrfs: deal with NULL srv_rsv in the delalloc inode reservation code
btrfs_update_inode is sometimes called with a null reservation.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2011-12-15 13:36:29 -05:00
Josef Bacik
e65cbb94e0 Btrfs: only set cache_generation if we setup the block group
A user reported a problem booting into a new kernel with the old format inodes.
He was panicing in cow_file_range while writing out the inode cache.  This is
because if the block group is not cached we'll just skip writing out the cache,
however if it gets dirtied again in the same transaction and it finished caching
we'd go ahead and write it out, but since we set cache_generation to the transid
we think we've already truncated it and will just carry on, running into
cow_file_range and blowing up.  We need to make sure we only set
cache_generation if we've done the truncate.  The user tested this patch and
verified that the panic no longer occured.  Thanks,

Reported-and-Tested-by: Klaus Bitto <klaus.bitto@gmail.com>
Signed-off-by: Josef Bacik <josef@redhat.com>
2011-12-15 11:04:24 -05:00
Josef Bacik
ee4d89f0c4 Btrfs: don't panic if orphan item already exists
I've been hitting this BUG_ON() in btrfs_orphan_add when running xfstest 269 in
a loop.  This is because we will add an orphan item, do the truncate, the
truncate will fail for whatever reason (*cough*ENOSPC*cough*) and then we're
left with an orphan item still in the fs.  Then we come back later to do another
truncate and it blows up because we already have an orphan item.  This is ok so
just fix the BUG_ON() to only BUG() if ret is not EEXIST.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
2011-12-15 11:04:24 -05:00
Josef Bacik
7041ee9728 Btrfs: fix leaked space in truncate
We were occasionaly leaking space when running xfstest 269.  This is because if
we failed to start the transaction in the truncate loop we'd just goto out, but
we need to break so that the inode is removed from the orphan list and the space
is properly freed.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
2011-12-15 11:04:23 -05:00
Josef Bacik
660d3f6cde Btrfs: fix how we do delalloc reservations and how we free reservations on error
Running xfstests 269 with some tracing my scripts kept spitting out errors about
releasing bytes that we didn't actually have reserved.  This took me down a huge
rabbit hole and it turns out the way we deal with reserved_extents is wrong,
we need to only be setting it if the reservation succeeds, otherwise the free()
method will come in and unreserve space that isn't actually reserved yet, which
can lead to other warnings and such.  The math was all working out right in the
end, but it caused all sorts of other issues in addition to making my scripts
yell and scream and generally make it impossible for me to track down the
original issue I was looking for.  The other problem is with our error handling
in the reservation code.  There are two cases that we need to deal with

1) We raced with free.  In this case free won't free anything because csum_bytes
is modified before we dro the lock in our reservation path, so free rightly
doesn't release any space because the reservation code may be depending on that
reservation.  However if we fail, we need the reservation side to do the free at
that point since that space is no longer in use.  So as it stands the code was
doing this fine and it worked out, except in case #2

2) We don't race with free.  Nobody comes in and changes anything, and our
reservation fails.  In this case we didn't reserve anything anyway and we just
need to clean up csum_bytes but not free anything.  So we keep track of
csum_bytes before we drop the lock and if it hasn't changed we know we can just
decrement csum_bytes and carry on.

Because of the case where we can race with free()'s since we have to drop our
spin_lock to do the reservation, I'm going to serialize all reservations with
the i_mutex.  We already get this for free in the heavy use paths, truncate and
file write all hold the i_mutex, just needed to add it to page_mkwrite and
various ioctl/balance things.  With this patch my space leak scripts no longer
scream bloody murder.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
2011-12-15 11:04:22 -05:00