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Maintain i_dio_count for all filesystems, not just those using DIO_LOCKING.
This these filesystems to also protect truncate against direct I/O requests
by using common code. Right now the only non-DIO_LOCKING filesystem that
appears to do so is XFS, which uses an opencoded variant of the i_dio_count
scheme.
Behaviour doesn't change for filesystems never calling inode_dio_wait.
For ext4 behaviour changes when using the dioread_nonlock option, which
previously was missing any protection between truncate and direct I/O reads.
For ocfs2 that handcrafted i_dio_count manipulations are replaced with
the common code now enable.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Let filesystems handle waiting for direct I/O requests themselves instead
of doing it beforehand. This means filesystem-specific locks to prevent
new dio referenes from appearing can be held. This is important to allow
generalizing i_dio_count to non-DIO_LOCKING filesystems.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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i_alloc_sem is a rather special rw_semaphore. It's the last one that may
be released by a non-owner, and it's write side is always mirrored by
real exclusion. It's intended use it to wait for all pending direct I/O
requests to finish before starting a truncate.
Replace it with a hand-grown construct:
- exclusion for truncates is already guaranteed by i_mutex, so it can
simply fall way
- the reader side is replaced by an i_dio_count member in struct inode
that counts the number of pending direct I/O requests. Truncate can't
proceed as long as it's non-zero
- when i_dio_count reaches non-zero we wake up a pending truncate using
wake_up_bit on a new bit in i_flags
- new references to i_dio_count can't appear while we are waiting for
it to read zero because the direct I/O count always needs i_mutex
(or an equivalent like XFS's i_iolock) for starting a new operation.
This scheme is much simpler, and saves the space of a spinlock_t and a
struct list_head in struct inode (typically 160 bits on a non-debug 64-bit
system).
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Reject zero sized reads as soon as we know our I/O length, and don't
borther with locks or allocations that might have to be cleaned up
otherwise.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Rewrite ext4_page_mkwrite() to use __block_page_mkwrite() helper. This
removes the need of using i_alloc_sem to avoid races with truncate which
seems to be the wrong locking order according to lock ordering documented in
mm/rmap.c. Also calling ext4_da_write_begin() as used by the old code seems to
be problematic because we can decide to flush delay-allocated blocks which
will acquire s_umount semaphore - again creating unpleasant lock dependency
if not directly a deadlock.
Also add a check for frozen filesystem so that we don't busyloop in page fault
when the filesystem is frozen.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Add a new rw_semaphore to protect bmap against truncate. Previous
i_alloc_sem was abused for this, but it's going away in this series.
Note that we can't simply use i_mutex, given that the swapon code
calls ->bmap under it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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The flags parameter went away in
d749519b444db985e40b897f73ce1898b11f997e
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Convert the inode reclaim shrinker to use the new per-sb shrinker
operations. This allows much bigger reclaim batches to be used, and
allows the XFS inode cache to be shrunk in proportion with the VFS
dentry and inode caches. This avoids the problem of the VFS caches
being shrunk significantly before the XFS inode cache is shrunk
resulting in imbalances in the caches during reclaim.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Now that the per-sb shrinker is responsible for shrinking 2 or more
caches, increase the batch size to keep econmies of scale for
shrinking each cache. Increase the shrinker batch size to 1024
objects.
To allow for a large increase in batch size, add a conditional
reschedule to prune_icache_sb() so that we don't hold the LRU spin
lock for too long. This mirrors the behaviour of the
__shrink_dcache_sb(), and allows us to increase the batch size
without needing to worry about problems caused by long lock hold
times.
To ensure that filesystems using the per-sb shrinker callouts don't
cause problems, document that the object freeing method must
reschedule appropriately inside loops.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Now we have a per-superblock shrinker implementation, we can add a
filesystem specific callout to it to allow filesystem internal
caches to be shrunk by the superblock shrinker.
Rather than perpetuate the multipurpose shrinker callback API (i.e.
nr_to_scan == 0 meaning "tell me how many objects freeable in the
cache), two operations will be added. The first will return the
number of objects that are freeable, the second is the actual
shrinker call.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Now that we have per-sb shrinkers with a lifecycle that is a subset
of the superblock lifecycle and can reliably detect a filesystem
being unmounted, there is not longer any race condition for the
iprune_sem to protect against. Hence we can remove it.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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With context based shrinkers, we can implement a per-superblock
shrinker that shrinks the caches attached to the superblock. We
currently have global shrinkers for the inode and dentry caches that
split up into per-superblock operations via a coarse proportioning
method that does not batch very well. The global shrinkers also
have a dependency - dentries pin inodes - so we have to be very
careful about how we register the global shrinkers so that the
implicit call order is always correct.
With a per-sb shrinker callout, we can encode this dependency
directly into the per-sb shrinker, hence avoiding the need for
strictly ordering shrinker registrations. We also have no need for
any proportioning code for the shrinker subsystem already provides
this functionality across all shrinkers. Allowing the shrinker to
operate on a single superblock at a time means that we do less
superblock list traversals and locking and reclaim should batch more
effectively. This should result in less CPU overhead for reclaim and
potentially faster reclaim of items from each filesystem.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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For improving insight into IO completion behaviour.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>
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The list of active AIL cursors uses a roll-your-own linked list with
special casing for the AIL push cursor. Simplify this code by
replacing the list with standard struct list_head lists, and use a
separate list_head to track the active cursors. This allows us to
treat the AIL push cursor as a generic cursor rather than as a
special case, further simplifying the code.
Further, fix the duplicate push cursor initialisation that the
special case handling was hiding, and clean up all the comments
around the active cursor list handling.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>
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xfs_trans_ail_cursor_set() doesn't set the cursor to the current log
item, it sets it to the next item. There is already a function for
doing this - xfs_trans_ail_cursor_next() - and the _set function is
simply a two line wrapper. Remove it and open code the setting of
the cursor in the two locations that call it to remove the
confusion.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>
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Delayed logging can insert tens of thousands of log items into the
AIL at the same LSN. When the committing of log commit records
occur, we can get insertions occurring at an LSN that is not at the
end of the AIL. If there are thousands of items in the AIL on the
tail LSN, each insertion has to walk the AIL to find the correct
place to insert the new item into the AIL. This can consume large
amounts of CPU time and block other operations from occurring while
the traversals are in progress.
To avoid this repeated walk, use a AIL cursor to record
where we should be inserting the new items into the AIL without
having to repeat the walk. The cursor infrastructure already
provides this functionality for push walks, so is a simple extension
of existing code. While this will not avoid the initial walk, it
will avoid repeating it tens of thousands of times during a single
checkpoint commit.
This version includes logic improvements from Christoph Hellwig.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>
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On xfs exports, nfsd is incorrectly returning ENOENT instead of
ESTALE on attempts to use a filehandle of a deleted file (spotted
with pynfs test PUTFH3). The ENOENT was coming from xfs_iget.
(It's tempting to wonder whether we should just map all xfs_iget
errors to ESTALE, but I don't believe so--xfs_iget can also return
ENOMEM at least, which we wouldn't want mapped to ESTALE.)
While we're at it, the other return of ENOENT in xfs_nfs_get_inode()
also looks wrong.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Alex Elder <aelder@sgi.com>
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Remove the second parameter to xfs_sb_count() since all callers of
the function set them.
Also, fix the header comment regarding it being called periodically.
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Alex Elder <aelder@sgi.com>
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The per-sb shrinker has the same requirement as the writeback
threads of ensuring that the superblock is usable and pinned for the
time it takes to run the work. Both need to take a passive reference
to the sb, take a read lock on the s_umount lock and then only
continue if an unmount is not in progress.
pin_sb_for_writeback() does this exactly, so move it to fs/super.c
and rename it to grab_super_passive() and exporting it via
fs/internal.h for all the VFS code to be able to use.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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With the inode LRUs moving to per-sb structures, there is no longer
a need for a global inode_lru_lock. The locking can be made more
fine-grained by moving to a per-sb LRU lock, isolating the LRU
operations of different filesytsems completely from each other.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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The inode unused list is currently a global LRU. This does not match
the other global filesystem cache - the dentry cache - which uses
per-superblock LRU lists. Hence we have related filesystem object
types using different LRU reclaimation schemes.
To enable a per-superblock filesystem cache shrinker, both of these
caches need to have per-sb unused object LRU lists. Hence this patch
converts the global inode LRU to per-sb LRUs.
The patch only does rudimentary per-sb propotioning in the shrinker
infrastructure, as this gets removed when the per-sb shrinker
callouts are introduced later on.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Before we split up the inode_lru_lock, the unused inode counter
needs to be made independent of the global inode_lru_lock. Convert
it to per-cpu counters to do this.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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... and simplify the living hell out of callers
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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d_splice_alias(NULL, dentry) is equivalent to d_add(dentry, NULL), NULL
so no need for that if (inode) ... in there (or ERR_PTR(0), for that
matter)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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just rewind it to the beginning before vfs_readdir() and be
done with that...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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never is...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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it never is...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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New helper (non-exported, fs/internal.h-only): __d_alloc(sb, name).
Allocates dentry, sets its ->d_sb to given superblock and sets
->d_op accordingly. Old d_alloc(NULL, name) callers are converted
to that (all of them know what superblock they want). d_alloc()
itself is left only for parent != NULl case; uses __d_alloc(),
inserts result into the list of parent's children.
Note that now ->d_sb is assign-once and never NULL *and*
->d_parent is never NULL either.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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folded into the only caller (kern_path_create())
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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combination of kern_path_parent() and lookup_create(). Does *not*
expose struct nameidata to caller. Syscalls converted to that...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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LOOKUP_PARENT is equivalent to it now
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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... it will be set in nd->flag for all cases with non-NULL nd
(i.e. when called from do_last()).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Instead of playing with removal of LOOKUP_OPEN, mangling (and
restoring) nd->path, just pass NULL to vfs_create(). The whole
point of what's being done there is to suppress any attempts
to open file by underlying fs, which is what nd == NULL indicates.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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->create() instances are much happier that way...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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All instances can cope with that now (and ceph one actually
starts working properly).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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a) check the right flags in ->create() (LOOKUP_OPEN, not LOOKUP_CREATE)
b) default (!LOOKUP_OPEN) open_flags is O_CREAT|O_EXCL|FMODE_READ, not 0
c) lookup_instantiate_filp() should be done only with LOOKUP_OPEN;
otherwise we need to issue CLOSE, lest we leak stateid on server.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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just open flags; switched to passing just those and
renamed to create_nfs_open_context()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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just dentry, please...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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instead of path_get()/path_put(), we can just use nfs_sb_{,de}active()
to pin the superblock down.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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... and get rid of a bogus typecast, while we are at it; it's not
just that we want a function returning int and not void, but cast
to pointer to function taking void * and returning void would be
(void (*)(void *)) and not (void *)(void *), TYVM...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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... now that inode_permission() can take MAY_NOT_BLOCK and handle it
properly.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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