- 21 Jul, 2011 22 commits
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Al Viro authored
Signed-off-by:Al Viro <viro@zeniv.linux.org.uk>
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Al Viro authored
we can find superblock easier, TYVM... Signed-off-by: -
Al Viro authored
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Al Viro authored
its first argument is const char * and it's really not modified... Signed-off-by: -
Al Viro authored
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Kay Sievers authored
Moving the event counter into the dynamically allocated 'struc seq_file' allows poll() support without the need to allocate its own tracking structure. All current users are switched over to use the new counter. Requested-by: Andrew Morton akpm@linux-foundation.org Acked-by:
NeilBrown <neilb@suse.de> Tested-by: Lucas De Marchi lucas.demarchi@profusion.mobi Signed-off-by:
Kay Sievers <kay.sievers@vrfy.org> Signed-off-by:
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Christoph Hellwig authored
For filesystems that delay their end_io processing we should keep our i_dio_count until the the processing is done. Enable this by moving the inode_dio_done call to the end_io handler if one exist. Note that the actual move to the workqueue for ext4 and XFS is not done in this patch yet, but left to the filesystem maintainers. At least for XFS it's not needed yet either as XFS has an internal equivalent to i_dio_count. Signed-off-by:
Christoph Hellwig <hch@lst.de> Signed-off-by:
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Christoph Hellwig authored
Simple filesystems always pass inode->i_sb_bdev as the block device argument, and never need a end_io handler. Let's simply things for them and for my grepping activity by dropping these arguments. The only thing not falling into that scheme is ext4, which passes and end_io handler without needing special flags (yet), but given how messy the direct I/O code there is use of __blockdev_direct_IO in one instead of two out of three cases isn't going to make a large difference anyway. Signed-off-by:
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Christoph Hellwig authored
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:
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Christoph Hellwig authored
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:
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Christoph Hellwig authored
Now that the last users is gone these can be removed. Signed-off-by:
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Christoph Hellwig authored
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:
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Christoph Hellwig authored
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:
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Jan Kara authored
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:
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Christoph Hellwig authored
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:
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Tobias Klauser authored
The flags parameter went away in d749519b444db985e40b897f73ce1898b11f997e Signed-off-by:
Tobias Klauser <tklauser@distanz.ch> Signed-off-by:
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Tomasz Stanislawski authored
The forward declaration of struct file_operations is added to avoid compilation warnings. Signed-off-by:
Tomasz Stanislawski <t.stanislaws@samsung.com> Signed-off-by:
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Dave Chinner authored
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:
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Dave Chinner authored
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:
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Dave Chinner authored
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:
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Dave Chinner authored
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:
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Dave Chinner authored
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:
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- 20 Jul, 2011 18 commits
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Dave Chinner authored
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:
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Dave Chinner authored
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:
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Dave Chinner authored
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:
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Dave Chinner authored
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:
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Dave Chinner authored
For shrinkers that have their own cond_resched* calls, having shrink_slab break the work down into small batches is not paticularly efficient. Add a custom batchsize field to the struct shrinker so that shrinkers can use a larger batch size if they desire. A value of zero (uninitialised) means "use the default", so behaviour is unchanged by this patch. Signed-off-by:
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Dave Chinner authored
When a shrinker returns -1 to shrink_slab() to indicate it cannot do any work given the current memory reclaim requirements, it adds the entire total_scan count to shrinker->nr. The idea ehind this is that whenteh shrinker is next called and can do work, it will do the work of the previously aborted shrinker call as well. However, if a filesystem is doing lots of allocation with GFP_NOFS set, then we get many, many more aborts from the shrinkers than we do successful calls. The result is that shrinker->nr winds up to it's maximum permissible value (twice the current cache size) and then when the next shrinker call that can do work is issued, it has enough scan count built up to free the entire cache twice over. This manifests itself in the cache going from full to empty in a matter of seconds, even when only a small part of the cache is needed to be emptied to free sufficient memory. Under metadata intensive workloads on ext4 and XFS, I'm seeing the VFS caches increase memory consumption up to 75% of memory (no page cache pressure) over a period of 30-60s, and then the shrinker empties them down to zero in the space of 2-3s. This cycle repeats over and over again, with the shrinker completely trashing the inode and dentry caches every minute or so the workload continues. This behaviour was made obvious by the shrink_slab tracepoints added earlier in the series, and made worse by the patch that corrected the concurrent accounting of shrinker->nr. To avoid this problem, stop repeated small increments of the total scan value from winding shrinker->nr up to a value that can cause the entire cache to be freed. We still need to allow it to wind up, so use the delta as the "large scan" threshold check - if the delta is more than a quarter of the entire cache size, then it is a large scan and allowed to cause lots of windup because we are clearly needing to free lots of memory. If it isn't a large scan then limit the total scan to half the size of the cache so that windup never increases to consume the whole cache. Reducing the total scan limit further does not allow enough wind-up to maintain the current levels of performance, whilst a higher threshold does not prevent the windup from freeing the entire cache under sustained workloads. Signed-off-by:
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Dave Chinner authored
shrink_slab() allows shrinkers to be called in parallel so the struct shrinker can be updated concurrently. It does not provide any exclusio for such updates, so we can get the shrinker->nr value increasing or decreasing incorrectly. As a result, when a shrinker repeatedly returns a value of -1 (e.g. a VFS shrinker called w/ GFP_NOFS), the shrinker->nr goes haywire, sometimes updating with the scan count that wasn't used, sometimes losing it altogether. Worse is when a shrinker does work and that update is lost due to racy updates, which means the shrinker will do the work again! Fix this by making the total_scan calculations independent of shrinker->nr, and making the shrinker->nr updates atomic w.r.t. to other updates via cmpxchg loops. Signed-off-by:
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Dave Chinner authored
It is impossible to understand what the shrinkers are actually doing without instrumenting the code, so add a some tracepoints to allow insight to be gained. Signed-off-by:
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Al Viro authored
... and simplify the living hell out of callers Signed-off-by: -
Al Viro authored
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 authored
just rewind it to the beginning before vfs_readdir() and be done with that... Signed-off-by: -
Al Viro authored
never is... Signed-off-by: -
Al Viro authored
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Al Viro authored
it never is... Signed-off-by: -
Al Viro authored
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 authored
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Al Viro authored
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Al Viro authored
folded into the only caller (kern_path_create()) Signed-off-by:
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