- 10 1月, 2012 2 次提交
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由 Al Viro 提交于
d_alloc_root() with iput() in case of allocation failure... Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 Dave Chinner 提交于
select_parent currently abuses the dentry cache LRU to provide cleanup features for child dentries that need to be freed. It moves them to the tail of the LRU, then tells shrink_dcache_parent() to calls __shrink_dcache_sb to unconditionally move them to a dispose list (as DCACHE_REFERENCED is ignored). __shrink_dcache_sb() has to relock the dentries to move them off the LRU onto the dispose list, but otherwise does not touch the dentries that select_parent() moved to the tail of the LRU. It then passses the dispose list to shrink_dentry_list() which tries to free the dentries. IOWs, the use of __shrink_dcache_sb() is superfluous - we can build exactly the same list of dentries for disposal directly in select_parent() and call shrink_dentry_list() instead of calling __shrink_dcache_sb() to do that. This means that we avoid long holds on the lru lock walking the LRU moving dentries to the dispose list We also avoid the need to relock each dentry just to move it off the LRU, reducing the numebr of times we lock each dentry to dispose of them in shrink_dcache_parent() from 3 to 2 times. Further, we remove one of the two callers of __shrink_dcache_sb(). This also means that __shrink_dcache_sb can be moved into back into prune_dcache_sb() and we no longer have to handle referenced dentries conditionally, simplifying the code. Signed-off-by: NDave Chinner <dchinner@redhat.com> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 04 1月, 2012 7 次提交
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由 Al Viro 提交于
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 Al Viro 提交于
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 Al Viro 提交于
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 Al Viro 提交于
the second victim... Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 Al Viro 提交于
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 Al Viro 提交于
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: NAl Viro <viro@zeniv.linux.org.uk>
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由 Al Viro 提交于
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: NAl Viro <viro@zeniv.linux.org.uk>
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- 07 12月, 2011 1 次提交
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由 Al Viro 提交于
__d_path() API is asking for trouble and in case of apparmor d_namespace_path() getting just that. The root cause is that when __d_path() misses the root it had been told to look for, it stores the location of the most remote ancestor in *root. Without grabbing references. Sure, at the moment of call it had been pinned down by what we have in *path. And if we raced with umount -l, we could have very well stopped at vfsmount/dentry that got freed as soon as prepend_path() dropped vfsmount_lock. It is safe to compare these pointers with pre-existing (and known to be still alive) vfsmount and dentry, as long as all we are asking is "is it the same address?". Dereferencing is not safe and apparmor ended up stepping into that. d_namespace_path() really wants to examine the place where we stopped, even if it's not connected to our namespace. As the result, it looked at ->d_sb->s_magic of a dentry that might've been already freed by that point. All other callers had been careful enough to avoid that, but it's really a bad interface - it invites that kind of trouble. The fix is fairly straightforward, even though it's bigger than I'd like: * prepend_path() root argument becomes const. * __d_path() is never called with NULL/NULL root. It was a kludge to start with. Instead, we have an explicit function - d_absolute_root(). Same as __d_path(), except that it doesn't get root passed and stops where it stops. apparmor and tomoyo are using it. * __d_path() returns NULL on path outside of root. The main caller is show_mountinfo() and that's precisely what we pass root for - to skip those outside chroot jail. Those who don't want that can (and do) use d_path(). * __d_path() root argument becomes const. Everyone agrees, I hope. * apparmor does *NOT* try to use __d_path() or any of its variants when it sees that path->mnt is an internal vfsmount. In that case it's definitely not mounted anywhere and dentry_path() is exactly what we want there. Handling of sysctl()-triggered weirdness is moved to that place. * if apparmor is asked to do pathname relative to chroot jail and __d_path() tells it we it's not in that jail, the sucker just calls d_absolute_path() instead. That's the other remaining caller of __d_path(), BTW. * seq_path_root() does _NOT_ return -ENAMETOOLONG (it's stupid anyway - the normal seq_file logics will take care of growing the buffer and redoing the call of ->show() just fine). However, if it gets path not reachable from root, it returns SEQ_SKIP. The only caller adjusted (i.e. stopped ignoring the return value as it used to do). Reviewed-by: NJohn Johansen <john.johansen@canonical.com> ACKed-by: NJohn Johansen <john.johansen@canonical.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk> Cc: stable@vger.kernel.org
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- 21 11月, 2011 1 次提交
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由 David Howells 提交于
To prevent an NFS server from being used to create a directory loop in an NFS superblock on the client, the following patch was committed: commit 18367501 Author: Al Viro <viro@zeniv.linux.org.uk> Date: Tue Jul 12 21:42:24 2011 -0400 Subject: fix loop checks in d_materialise_unique() This causes ELOOP to be reported to anyone trying to access the dentry that would otherwise cause the kernel to complete the loop. However, no indication is given to the caller as to why an operation that ought to work doesn't. The fault is with the kernel, which doesn't want to try and solve the problem as it gets horrendously messy if there's another mountpoint somewhere in the trees being spliced that can't be moved[*]. [*] The real problem is that we don't handle the excision of a subtree that gets moved _out_ of what we can see. This can happen on the server where a directory is merely moved between two other dirs on the same filesystem, but where destination dir is not accessible by the client. So, given the choice to return ELOOP rather than trying to reconfigure the dentry tree, we should give the caller some indication of why they aren't being allowed to make what should be a legitimate request and log a message. Signed-off-by: NDavid Howells <dhowells@redhat.com> Acked-by: NSachin Prabhu <sprabhu@redhat.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 08 11月, 2011 1 次提交
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由 Al Viro 提交于
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 02 11月, 2011 1 次提交
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由 Sage Weil 提交于
This adds a d_prune dentry operation that is called by the VFS prior to pruning (i.e. unhashing and killing) a hashed dentry from the dcache. Wrap dentry_lru_del() and use the new _prune() helper in the cases where we are about to unhash and kill the dentry. This will be used by Ceph to maintain a flag indicating whether the complete contents of a directory are contained in the dcache, allowing it to satisfy lookups and readdir without addition server communication. Renumber a few DCACHE_* #defines to group DCACHE_OP_PRUNE with the other DCACHE_OP_ bits. Signed-off-by: NSage Weil <sage@newdream.net> Signed-off-by: NChristoph Hellwig <hch@lst.de>
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- 07 8月, 2011 1 次提交
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由 Linus Torvalds 提交于
Gcc tends to generate better code with small integers, including the DCACHE_xyz flag tests - so move the common ones to be first in the list. Also just remove the unused DCACHE_INOTIFY_PARENT_WATCHED and DCACHE_AUTOFS_PENDING values, their users no longer exists in the source tree. And add a "unlikely()" to the DCACHE_OP_COMPARE test, since we want the common case to be a nice straight-line fall-through. Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 04 8月, 2011 1 次提交
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由 Randy Dunlap 提交于
Fix new kernel-doc warning in fs/dcache.c: Warning(fs/dcache.c:797): No description found for parameter 'sb' Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 01 8月, 2011 3 次提交
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由 David Howells 提交于
Reorganise shrink_dcache_for_umount_subtree() in light of the demise of dcache_lock. Without that dcache_lock, there is no need for the batching of removal of dentries from the system under it (we wanted to make intensive use of the locked data whilst we held it, but didn't want to hold it for long at a time). This works, provided the preceding patch is correct in its removal of locking on dentry->d_lock on the basis that no one should be locking these dentries any more as the whole superblock is defunct. With this patch, the calls to dentry_lru_del() and __d_shrink() are placed at the point where each dentry is detached handled. It is possible that, as an alternative, the batching should still be done - but only for dentry_lru_del() of all a dentry's children in one go. In such a case, the batching would be done under dcache_lru_lock. Signed-off-by: NDavid Howells <dhowells@redhat.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 David Howells 提交于
Locks of the dcache_lock were replaced by locks of dentry->d_lock in commits such as: 23044507 2fd6b7f5 as part of the RCU-based pathwalk changes, despite the fact that the caller (shrink_dcache_for_umount()) notes in the banner comment the reasons that d_lock is not necessary in these functions: /* * destroy the dentries attached to a superblock on unmounting * - we don't need to use dentry->d_lock because: * - the superblock is detached from all mountings and open files, so the * dentry trees will not be rearranged by the VFS * - s_umount is write-locked, so the memory pressure shrinker will ignore * any dentries belonging to this superblock that it comes across * - the filesystem itself is no longer permitted to rearrange the dentries * in this superblock */ So remove these locks. If the locks are actually necessary, then this banner comment should be altered instead. The hash table chains are protected by 1-bit locks in the hash table heads, so those shouldn't be a problem. Note that to make this work, __d_drop() has to be split so that the RCUwalk barrier can be avoided. This causes problems otherwise as it has an assertion that dentry->d_lock is locked - but there is no need for that as no one else can be trying to access this dentry, except to step over it (and that should be handled by d_free(), I think). Signed-off-by: NDavid Howells <dhowells@redhat.com> Cc: Nick Piggin <npiggin@kernel.dk> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 David Howells 提交于
Remove the detached-dentry counter from shrink_dcache_for_umount_subtree() as the value it computes is no longer used as of commit 312d3ca8 which made the nr_dentry counters summed per-CPU rather than global atomic. Signed-off-by: NDavid Howells <dhowells@redhat.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 27 7月, 2011 1 次提交
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由 Jeff Layton 提交于
Adding a comment to d_materialise_unique per Al's request... d_move and __d_move have some pretty substantial locking requirements, but they are not clearly documented. Add some comments spelling them out. Also, document the requirement for the i_mutex of the parent in d_materialise_unique. Cc: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: NJeff Layton <jlayton@redhat.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 22 7月, 2011 1 次提交
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由 Linus Torvalds 提交于
It seems to hurt performance in real life. Yes, the inode will be used later, but the conditional doesn't seem to predict all that well (negative dentries are not uncommon) and it looks like the cost of prefetching is simply higher than depending on the cache doing the right thing. As usual. Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 21 7月, 2011 3 次提交
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由 Al Viro 提交于
->d_parent is never NULL... Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 Al Viro 提交于
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 Dave Chinner 提交于
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: NDave Chinner <dchinner@redhat.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 20 7月, 2011 3 次提交
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由 Al Viro 提交于
... and simplify the living hell out of callers Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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由 Al Viro 提交于
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: NAl Viro <viro@zeniv.linux.org.uk>
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由 Josef Bacik 提交于
Btrfs (and I'd venture most other fs's) stores its indexes in nice disk order for readdir, but unfortunately in the case of anything that stats the files in order that readdir spits back (like oh say ls) that means we still have to do the normal lookup of the file, which means looking up our other index and then looking up the inode. What I want is a way to create dummy dentries when we find them in readdir so that when ls or anything else subsequently does a stat(), we already have the location information in the dentry and can go straight to the inode itself. The lookup stuff just assumes that if it finds a dentry it is done, it doesn't perform a lookup. So add a DCACHE_NEED_LOOKUP flag so that the lookup code knows it still needs to run i_op->lookup() on the parent to get the inode for the dentry. I have tested this with btrfs and I went from something that looks like this http://people.redhat.com/jwhiter/ls-noreada.png To this http://people.redhat.com/jwhiter/ls-good.png Thats a savings of 1300 seconds, or 22 minutes. That is a significant savings. Thanks, Signed-off-by: NJosef Bacik <josef@redhat.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 15 7月, 2011 1 次提交
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由 Al Viro 提交于
Both __d_unalias() and __d_materialise_dentry() need loop prevention. Grab rename_lock in caller, check for loops there... As a side benefit, we have dentry_lock_for_move() called only under rename_lock, which seriously reduces deadlock potential of the execrable "locking order" used for ->d_lock. Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 25 5月, 2011 1 次提交
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由 Ying Han 提交于
Change each shrinker's API by consolidating the existing parameters into shrink_control struct. This will simplify any further features added w/o touching each file of shrinker. [akpm@linux-foundation.org: fix build] [akpm@linux-foundation.org: fix warning] [kosaki.motohiro@jp.fujitsu.com: fix up new shrinker API] [akpm@linux-foundation.org: fix xfs warning] [akpm@linux-foundation.org: update gfs2] Signed-off-by: NYing Han <yinghan@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Minchan Kim <minchan.kim@gmail.com> Acked-by: NPavel Emelyanov <xemul@openvz.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Acked-by: NRik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Hugh Dickins <hughd@google.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 21 5月, 2011 1 次提交
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由 Linus Torvalds 提交于
Commit e66eed65 ("list: remove prefetching from regular list iterators") removed the include of prefetch.h from list.h, which uncovered several cases that had apparently relied on that rather obscure header file dependency. So this fixes things up a bit, using grep -L linux/prefetch.h $(git grep -l '[^a-z_]prefetchw*(' -- '*.[ch]') grep -L 'prefetchw*(' $(git grep -l 'linux/prefetch.h' -- '*.[ch]') to guide us in finding files that either need <linux/prefetch.h> inclusion, or have it despite not needing it. There are more of them around (mostly network drivers), but this gets many core ones. Reported-by: NStephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 26 4月, 2011 1 次提交
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由 Christoph Hellwig 提交于
Now that the whole dcache_hash_bucket crap is gone, go all the way and also remove the weird locking layering violations for locking the hash buckets. Add hlist_bl_lock/unlock helpers to move the locking into the list abstraction instead of requiring each caller to open code it. After all allowing for the bit locks is the whole point of these helpers over the plain hlist variant. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 24 4月, 2011 2 次提交
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由 Linus Torvalds 提交于
The dentry hashing rules have been really quite complicated for a long while, in odd ways. That made functions like __d_drop() very fragile and non-obvious. In particular, whether a dentry was hashed or not was indicated with an explicit DCACHE_UNHASHED bit. That's despite the fact that the hash abstraction that the dentries use actually have a 'is this entry hashed or not' model (which is a simple test of the 'pprev' pointer). The reason that was done is because we used the normal 'is this entry unhashed' model to mark whether the dentry had _ever_ been hashed in the dentry hash tables, and that logic goes back many years (commit b3423415: "dcache: avoid RCU for never-hashed dentries"). That, in turn, meant that __d_drop had totally different unhashing logic for the dentry hash table case and for the anonymous dcache case, because in order to use the "is this dentry hashed" logic as a flag for whether it had ever been on the RCU hash table, we had to unhash such a dentry differently so that we'd never think that it wasn't 'unhashed' and wouldn't be free'd correctly. That's just insane. It made the logic really hard to follow, when there were two different kinds of "unhashed" states, and one of them (the one that used "list_bl_unhashed()") really had nothing at all to do with being unhashed per se, but with a very subtle lifetime rule instead. So turn all of it around, and make it logical. Instead of having a DENTRY_UNHASHED bit in d_flags to indicate whether the dentry is on the hash chains or not, use the hash chain unhashed logic for that. Suddenly "d_unhashed()" just uses "list_bl_unhashed()", and everything makes sense. And for the lifetime rule, just use an explicit DENTRY_RCUACCEES bit. If we ever insert the dentry into the dentry hash table so that it is visible to RCU lookup, we mark it DENTRY_RCUACCESS to show that it now needs the RCU lifetime rules. Now suddently that test at dentry free time makes sense too. And because unhashing now is sane and doesn't depend on where the dentry got unhashed from (because the dentry hash chain details doesn't have some subtle side effects), we can re-unify the __d_drop() logic and use common code for the unhashing. Also fix one more open-coded hash chain bit_spin_lock() that I missed in the previous chain locking cleanup commit. Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Linus Torvalds 提交于
It's a useless abstraction for 'hlist_bl_head', and it doesn't actually help anything - quite the reverse. All the users end up having to know about the hlist_bl_head details anyway, using 'struct hlist_bl_node *' etc. So it just makes the code look confusing. And the cost of it is extra '&b->head' syntactic noise, but more importantly it spuriously makes the hash table dentry list look different from the per-superblock DCACHE_DISCONNECTED dentry list. As a result, the code ended up using ad-hoc locking for one case and special helper functions for what is really another totally identical case in the very same function. Make it all look and work the same. Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 15 4月, 2011 1 次提交
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由 Linus Torvalds 提交于
The case we should be verifying when updating the dentry name is that the _parent_ inode (the directory) semaphore is held, not the semaphore for the dentry itself. It's the directory locking that rename and readdir() etc all care about. The comment just above even says so - but then the BUG_ON() still checked the dentry inode itself. Very few people noticed, because this helper function really isn't used for very much, so you had to be using ncpfs to ever hit it. I think I should just remove the BUG_ON (the function really has just one user), but let's run with it fixed for a while before getting rid of it entirely. Reported-and-tested-by: NBongani Hlope <bonganih@bankservafrica.com> Reported-and-tested-by: NBernd Feige <bernd.feige@uniklinik-freiburg.de> Cc: Petr Vandrovec <petr@vandrovec.name>, Cc: Arnd Bergmann <arnd@arndb.de> Cc: Christoph Hellwig <hch@lst.de> Cc: Nick Piggin <npiggin@kernel.dk> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 18 3月, 2011 1 次提交
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由 Josef Bacik 提交于
While trying to track down some NFS problems with BTRFS, I kept noticing I was getting -EACCESS for no apparent reason. Eric Paris and printk() helped me figure out that it was SELinux that was giving me grief, with the following denial type=AVC msg=audit(1290013638.413:95): avc: denied { 0x800000 } for pid=1772 comm="nfsd" name="" dev=sda1 ino=256 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:unlabeled_t:s0 tclass=file Turns out this is because in d_obtain_alias if we can't find an alias we create one and do all the normal instantiation stuff, but we don't do the security_d_instantiate. Usually we are protected from getting a hashed dentry that hasn't yet run security_d_instantiate() by the parent's i_mutex, but obviously this isn't an option there, so in order to deal with the case that a second thread comes in and finds our new dentry before we get to run security_d_instantiate(), we go ahead and call it if we find a dentry already. Eric assures me that this is ok as the code checks to see if the dentry has been initialized already so calling security_d_instantiate() against the same dentry multiple times is ok. With this patch I'm no longer getting errant -EACCESS values. Signed-off-by: NJosef Bacik <josef@redhat.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 16 3月, 2011 2 次提交
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由 Trond Myklebust 提交于
The new vfs locking scheme introduced in 2.6.38 breaks NFS sillyrename because the latter relies on being able to determine the parent directory of the dentry in the ->iput() callback in order to send the appropriate unlink rpc call. Looking at the code that cares about races with dput(), there doesn't seem to be anything that specifically uses d_parent as a test for whether or not there is a race: - __d_lookup_rcu(), __d_lookup() all test for d_hashed() after d_parent - shrink_dcache_for_umount() is safe since nothing else can rearrange the dentries in that super block. - have_submount(), select_parent() and d_genocide() can test for a deletion if we set the DCACHE_DISCONNECTED flag when the dentry is removed from the parent's d_subdirs list. Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com> Cc: stable@kernel.org (2.6.38, needs commit c826cb7d "dcache.c: create helper function for duplicated functionality" ) Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Linus Torvalds 提交于
This creates a helper function for he "try to ascend into the parent directory" case, which was written out in triplicate before. With all the locking and subtle sequence number stuff, we really don't want to duplicate that kind of code. Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 10 3月, 2011 1 次提交
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由 J. Bruce Fields 提交于
Without this patch, inodes are not promptly freed on last close of an unlinked file by an nfs client: client$ mount -tnfs4 server:/export/ /mnt/ client$ tail -f /mnt/FOO ... server$ df -i /export server$ rm /export/FOO (^C the tail -f) server$ df -i /export server$ echo 2 >/proc/sys/vm/drop_caches server$ df -i /export the df's will show that the inode is not freed on the filesystem until the last step, when it could have been freed after killing the client's tail -f. On-disk data won't be deallocated either, leading to possible spurious ENOSPC. This occurs because when the client does the close, it arrives in a compound with a putfh and a close, processed like: - putfh: look up the filehandle. The only alias found for the inode will be DCACHE_UNHASHED alias referenced by the filp this, so it creates a new DCACHE_DISCONECTED dentry and returns that instead. - close: closes the existing filp, which is destroyed immediately by dput() since it's DCACHE_UNHASHED. - end of the compound: release the reference to the current filehandle, and dput() the new DCACHE_DISCONECTED dentry, which gets put on the unused list instead of being destroyed immediately. Nick Piggin suggested fixing this by allowing d_obtain_alias to return the unhashed dentry that is referenced by the filp, instead of making it create a new dentry. Leave __d_find_alias() alone to avoid changing behavior of other callers. Also nfsd doesn't need all the checks of __d_find_alias(); any dentry, hashed or unhashed, disconnected or not, should work. Signed-off-by: NJ. Bruce Fields <bfields@redhat.com> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 17 2月, 2011 1 次提交
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由 Namhyung Kim 提交于
dcache-locking.txt is not exist any more, and the path was not correct anyway. Fix it. Signed-off-by: NNamhyung Kim <namhyung@gmail.com> Signed-off-by: NJiri Kosina <jkosina@suse.cz>
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- 23 1月, 2011 1 次提交
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由 Randy Dunlap 提交于
Fix new fs/dcache.c kernel-doc warnings: Warning(fs/dcache.c:184): No description found for parameter 'dentry' Warning(fs/dcache.c:296): No description found for parameter 'parent' Warning(fs/dcache.c:1985): No description found for parameter 'dparent' Warning(fs/dcache.c:1985): Excess function parameter 'parent' description in 'd_validate' Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Nick Piggin <npiggin@kernel.dk> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 16 1月, 2011 1 次提交
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由 David Howells 提交于
Add a dentry op (d_automount) to handle automounting directories rather than abusing the follow_link() inode operation. The operation is keyed off a new dentry flag (DCACHE_NEED_AUTOMOUNT). This also makes it easier to add an AT_ flag to suppress terminal segment automount during pathwalk and removes the need for the kludge code in the pathwalk algorithm to handle directories with follow_link() semantics. The ->d_automount() dentry operation: struct vfsmount *(*d_automount)(struct path *mountpoint); takes a pointer to the directory to be mounted upon, which is expected to provide sufficient data to determine what should be mounted. If successful, it should return the vfsmount struct it creates (which it should also have added to the namespace using do_add_mount() or similar). If there's a collision with another automount attempt, NULL should be returned. If the directory specified by the parameter should be used directly rather than being mounted upon, -EISDIR should be returned. In any other case, an error code should be returned. The ->d_automount() operation is called with no locks held and may sleep. At this point the pathwalk algorithm will be in ref-walk mode. Within fs/namei.c itself, a new pathwalk subroutine (follow_automount()) is added to handle mountpoints. It will return -EREMOTE if the automount flag was set, but no d_automount() op was supplied, -ELOOP if we've encountered too many symlinks or mountpoints, -EISDIR if the walk point should be used without mounting and 0 if successful. The path will be updated to point to the mounted filesystem if a successful automount took place. __follow_mount() is replaced by follow_managed() which is more generic (especially with the patch that adds ->d_manage()). This handles transits from directories during pathwalk, including automounting and skipping over mountpoints (and holding processes with the next patch). __follow_mount_rcu() will jump out of RCU-walk mode if it encounters an automount point with nothing mounted on it. follow_dotdot*() does not handle automounts as you don't want to trigger them whilst following "..". I've also extracted the mount/don't-mount logic from autofs4 and included it here. It makes the mount go ahead anyway if someone calls open() or creat(), tries to traverse the directory, tries to chdir/chroot/etc. into the directory, or sticks a '/' on the end of the pathname. If they do a stat(), however, they'll only trigger the automount if they didn't also say O_NOFOLLOW. I've also added an inode flag (S_AUTOMOUNT) so that filesystems can mark their inodes as automount points. This flag is automatically propagated to the dentry as DCACHE_NEED_AUTOMOUNT by __d_instantiate(). This saves NFS and could save AFS a private flag bit apiece, but is not strictly necessary. It would be preferable to do the propagation in d_set_d_op(), but that doesn't normally have access to the inode. [AV: fixed breakage in case if __follow_mount_rcu() fails and nameidata_drop_rcu() succeeds in RCU case of do_lookup(); we need to fall through to non-RCU case after that, rather than just returning with ungrabbed *path] Signed-off-by: NDavid Howells <dhowells@redhat.com> Was-Acked-by: NIan Kent <raven@themaw.net> Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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