- 29 Jun, 2013 40 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
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Al Viro authored
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Al Viro authored
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Al Viro authored
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Al Viro authored
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Al Viro authored
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Jeff Layton authored
There's no reason we have to protect the blocked_hash and file_lock_list with the same spinlock. With the tests I have, breaking it in two gives a barely measurable performance benefit, but it seems reasonable to make this locking as granular as possible. Signed-off-by:
Jeff Layton <jlayton@redhat.com> Signed-off-by:
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Jeff Layton authored
Currently, the hashing that the locking code uses to add these values to the blocked_hash is simply calculated using fl_owner field. That's valid in most cases except for server-side lockd, which validates the owner of a lock based on fl_owner and fl_pid. In the case where you have a small number of NFS clients doing a lot of locking between different processes, you could end up with all the blocked requests sitting in a very small number of hash buckets. Add a new lm_owner_key operation to the lock_manager_operations that will generate an unsigned long to use as the key in the hashtable. That function is only implemented for server-side lockd, and simply XORs the fl_owner and fl_pid. Signed-off-by:
J. Bruce Fields <bfields@fieldses.org> Signed-off-by:
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Jeff Layton authored
Break up the blocked_list into a hashtable, using the fl_owner as a key. This speeds up searching the hash chains, which is especially significant for deadlock detection. Note that the initial implementation assumes that hashing on fl_owner is sufficient. In most cases it should be, with the notable exception being server-side lockd, which compares ownership using a tuple of the nlm_host and the pid sent in the lock request. So, this may degrade to a single hash bucket when you only have a single NFS client. That will be addressed in a later patch. The careful observer may note that this patch leaves the file_lock_list alone. There's much less of a case for turning the file_lock_list into a hashtable. The only user of that list is the code that generates /proc/locks, and it always walks the entire list. Signed-off-by:
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Jeff Layton authored
Testing has shown that iterating over the blocked_list for deadlock detection turns out to be a bottleneck. In order to alleviate that, begin the process of turning it into a hashtable. We start by turning the fl_link into a hlist_node and the global lists into hlists. A later patch will do the conversion of the blocked_list to a hashtable. Signed-off-by:
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Jeff Layton authored
Since we always hold the i_lock when inserting a new waiter onto the fl_block list, we can avoid taking the global lock at all if we find that it's empty when we go to wake up blocked waiters. Signed-off-by:
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Jeff Layton authored
Having a global lock that protects all of this code is a clear scalability problem. Instead of doing that, move most of the code to be protected by the i_lock instead. The exceptions are the global lists that the ->fl_link sits on, and the ->fl_block list. ->fl_link is what connects these structures to the global lists, so we must ensure that we hold those locks when iterating over or updating these lists. Furthermore, sound deadlock detection requires that we hold the blocked_list state steady while checking for loops. We also must ensure that the search and update to the list are atomic. For the checking and insertion side of the blocked_list, push the acquisition of the global lock into __posix_lock_file and ensure that checking and update of the blocked_list is done without dropping the lock in between. On the removal side, when waking up blocked lock waiters, take the global lock before walking the blocked list and dequeue the waiters from the global list prior to removal from the fl_block list. With this, deadlock detection should be race free while we minimize excessive file_lock_lock thrashing. Finally, in order to avoid a lock inversion problem when handling /proc/locks output we must ensure that manipulations of the fl_block list are also protected by the file_lock_lock. Signed-off-by:
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Jeff Layton authored
Move the fl_link list handling routines into a separate set of helpers. Also ensure that locks and requests are always put on global lists last (after fully initializing them) and are taken off before unintializing them. Signed-off-by:
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Jeff Layton authored
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Jeff Layton authored
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Jeff Layton authored
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Jeff Layton authored
commit 66189be7 (CIFS: Fix VFS lock usage for oplocked files) exported the locks_delete_block symbol. There's already an exported helper function that provides this capability however, so make cifs use that instead and turn locks_delete_block back into a static function. Note that if fl->fl_next == NULL then this lock has already been through locks_delete_block(), so we should be OK to ignore an ENOENT error here and simply not retry the lock. Cc: Pavel Shilovsky <piastryyy@gmail.com> Signed-off-by:
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Jeff Layton authored
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Linus Torvalds authored
Instances either don't look at it at all (the majority of cases) or only want it to find the superblock (which can be had as dentry->d_sb). A few cases that want more are actually safe with dentry->d_inode - the only precaution needed is the check that it hadn't been replaced with NULL by rmdir() or by overwriting rename(), which case should be simply treated as cache miss. Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by:
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Dan Carpenter authored
"chunk_size" is an unsigned int and "pos" is an unsigned long. The "& ~(chunk_size-1)" operation clears the high 32 bits unintentionally. The ALIGN() macro does the correct thing. Signed-off-by:
Dan Carpenter <dan.carpenter@oracle.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org>
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Al Viro authored
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Al Viro authored
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Al Viro authored
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Al Viro authored
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Al Viro authored
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Al Viro authored
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Al Viro authored
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Al Viro authored
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Al Viro authored
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Al Viro authored
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Al Viro authored
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Al Viro authored
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Al Viro authored
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Al Viro authored
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Al Viro authored
... especially since there's no way to get that sucker on the list fsnotify_fasync() works with - the only thing adding to it is fsnotify_fasync() itself and it's never called for fanotify files while they are opened. Signed-off-by: -
Al Viro authored
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Al Viro authored
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Al Viro authored
the only remaining caller (in ncpfs) is guaranteed to return 0 - we only hit it if we'd just checked that there's no dentry with such name. Signed-off-by:
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