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path: root/fs/dcache.c
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* Fix NULL pointer dereference in proc_sys_compareLinus Torvalds2008-09-29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The VFS interface for the 'd_compare()' is a bit special (read: 'odd'), because it really just essentially replaces a memcmp(). The filesystem is supposed to just compare the two names with whatever case-independent or other function. And when I say 'is supposed to', I obviously mean that 'procfs does odd things, and actually looks at the dentry that we don't even pass down, rather than just the name'. Which results in problems, because we actually call d_compare before we have even verified that the dentry is still hashed at all. And that causes a problm since the inode that procfs looks at may have been free'd and the d_inode pointer is NULL. procfs just assumes that all dentries are positive, since procfs itself never generates a negative one. But memory pressure will still result in the dentry getting torn down, and as it is removed by RCU, it still remains visible on some lists - and to d_compare. If the filesystem just did a name comparison, we wouldn't care. And we could just fix procfs to know about negative dentries too. But rather than have the low-level filesystems know about internal VFS details, just move the check for a unhashed dentry up a bit, so that we will only call d_compare on dentries that are still active. The actual oops this caused didn't look like a NULL pointer dereference because procfs did a 'container_of(inode, struct proc_inode, vfs_inode)' to get at its internal proc_inode information from the inode pointer, and accessed a field below the inode. So the oops would look something like BUG: unable to handle kernel paging request at fffffffffffffff0 IP: [<ffffffff802bc6c6>] proc_sys_compare+0x36/0x50 and was seen on both x86-64 (Alexey Dobriyan and Hugh Dickins) and ppc64 (Hugh Dickins). Reported-by: Alexey Dobriyan <adobriyan@gmail.com> Acked-by: Hugh Dickins <hugh@veritas.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Reviewed-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-of-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] change d_add_ci argument orderingChristoph Hellwig2008-08-25
| | | | | | | | As pointed out during review d_add_ci argument order should match d_add, so switch the dentry and inode arguments. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* dcache: Add case-insensitive support d_ci_add() routineBarry Naujok2008-07-28
| | | | | | | | | | | | | | | | This add a dcache entry to the dcache for lookup, but changing the name that is associated with the entry rather than the one passed in to the lookup routine. First, it sees if the case-exact match already exists in the dcache and uses it if one exists. Otherwise, it allocates a new node with the new name and splices it into the dcache. Original code from ntfs_lookup in fs/ntfs/namei.c by Anton Altaparmakov. Signed-off-by: Barry Naujok <bnaujok@sgi.com> Signed-off-by: Anton Altaparmakov <aia21@cantab.net> Acked-by: Christoph Hellwig <hch@infradead.org>
* vfs: add cond_resched_lock while scanning dentry LRU listsKentaro Makita2008-07-26
| | | | | | | | | | Add cond_resched_lock(&dcache_lock) while scanning LRU lists on superblocks in __shrink_dcache_sb() Signed-off-by: Kentaro Makita <k-makita@np.css.fujitsu.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fix soft lock up at NFS mount via per-SB LRU-list of unused dentriesKentaro Makita2008-07-24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [Summary] Split LRU-list of unused dentries to one per superblock to avoid soft lock up during NFS mounts and remounting of any filesystem. Previously I posted here: http://lkml.org/lkml/2008/3/5/590 [Descriptions] - background dentry_unused is a list of dentries which are not referenced. dentry_unused grows up when references on directories or files are released. This list can be very long if there is huge free memory. - the problem When shrink_dcache_sb() is called, it scans all dentry_unused linearly under spin_lock(), and if dentry->d_sb is differnt from given superblock, scan next dentry. This scan costs very much if there are many entries, and very ineffective if there are many superblocks. IOW, When we need to shrink unused dentries on one dentry, but scans unused dentries on all superblocks in the system. For example, we scan 500 dentries to unmount a filesystem, but scans 1,000,000 or more unused dentries on other superblocks. In our case , At mounting NFS*, shrink_dcache_sb() is called to shrink unused dentries on NFS, but scans 100,000,000 unused dentries on superblocks in the system such as local ext3 filesystems. I hear NFS mounting took 1 min on some system in use. * : NFS uses virtual filesystem in rpc layer, so NFS is affected by this problem. 100,000,000 is possible number on large systems. Per-superblock LRU of unused dentried can reduce the cost in reasonable manner. - How to fix I found this problem is solved by David Chinner's "Per-superblock unused dentry LRU lists V3"(1), so I rebase it and add some fix to reclaim with fairness, which is in Andrew Morton's comments(2). 1) http://lkml.org/lkml/2006/5/25/318 2) http://lkml.org/lkml/2006/5/25/320 Split LRU-list of unused dentries to each superblocks. Then, NFS mounting will check dentries under a superblock instead of all. But this spliting will break LRU of dentry-unused. So, I've attempted to make reclaim unused dentrins with fairness by calculate number of dentries to scan on this sb based on following way number of dentries to scan on this sb = count * (number of dentries on this sb / number of dentries in the machine) - ToDo - I have to measuring performance number and do stress tests. - When unmount occurs during prune_dcache(), scanning on same superblock, It is unable to reach next superblock because it is gone away. We restart scannig superblock from first one, it causes unfairness of reclaim unused dentries on first superblock. But I think this happens very rarely. - Test Results Result on 6GB boxes with excessive unused dentries. Without patch: $ cat /proc/sys/fs/dentry-state 10181835 10180203 45 0 0 0 # mount -t nfs 10.124.60.70:/work/kernel-src nfs real 0m1.830s user 0m0.001s sys 0m1.653s With this patch: $ cat /proc/sys/fs/dentry-state 10236610 10234751 45 0 0 0 # mount -t nfs 10.124.60.70:/work/kernel-src nfs real 0m0.106s user 0m0.002s sys 0m0.032s [akpm@linux-foundation.org: fix comments] Signed-off-by: Kentaro Makita <k-makita@np.css.fujitsu.com> Cc: Neil Brown <neilb@suse.de> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: David Chinner <dgc@sgi.com> Cc: "J. Bruce Fields" <bfields@fieldses.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [patch 2/3] vfs: dcache cleanupsMiklos Szeredi2008-06-23
| | | | | | | Comment from Al Viro: add prepend_name() wrapper. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* [patch 1/3] vfs: dcache sparse fixesMiklos Szeredi2008-06-23
| | | | | | | | | | | | | | | | | | | Fix the following sparse warnings: fs/dcache.c:2183:19: warning: symbol 'filp_cachep' was not declared. Should it be static? fs/dcache.c:115:3: warning: context imbalance in 'dentry_iput' - unexpected unlock fs/dcache.c:188:2: warning: context imbalance in 'dput' - different lock contexts for basic block fs/dcache.c:400:2: warning: context imbalance in 'prune_one_dentry' - different lock contexts for basic block fs/dcache.c:431:22: warning: context imbalance in 'prune_dcache' - different lock contexts for basic block fs/dcache.c:563:2: warning: context imbalance in 'shrink_dcache_sb' - different lock contexts for basic block fs/dcache.c:1385:6: warning: context imbalance in 'd_delete' - wrong count at exit fs/dcache.c:1636:2: warning: context imbalance in '__d_unalias' - unexpected unlock fs/dcache.c:1735:2: warning: context imbalance in 'd_materialise_unique' - different lock contexts for basic block Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Reviewed-by: Matthew Wilcox <willy@linux.intel.com> Acked-by: Christoph Hellwig <hch@infradead.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* [patch 3/3] vfs: make d_path() consistent across mount operationsAndreas Gruenbacher2008-06-23
| | | | | | | | | | | | | | | | | | The path that __d_path() computes can become slightly inconsistent when it races with mount operations: it grabs the vfsmount_lock when traversing mount points but immediately drops it again, only to re-grab it when it reaches the next mount point. The result is that the filename computed is not always consisent, and the file may never have had that name. (This is unlikely, but still possible.) Fix this by grabbing the vfsmount_lock for the whole duration of __d_path(). Signed-off-by: Andreas Gruenbacher <agruen@suse.de> Signed-off-by: John Johansen <jjohansen@suse.de> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Acked-by: Christoph Hellwig <hch@infradead.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* [patch 2/4] fs: make struct file arg to d_path constJan Engelhardt2008-06-23
| | | | | | | Signed-off-by: Jan Engelhardt <jengelh@medozas.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* [patch 2/7] vfs: mountinfo: add seq_file_root()Miklos Szeredi2008-04-23
| | | | | | | | | | | | | Add a new function: seq_file_root() This is similar to seq_path(), but calculates the path relative to the given root, instead of current->fs->root. If the path was unreachable from root, then modify the root parameter to reflect this. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* [patch 1/7] vfs: mountinfo: add dentry_path()Ram Pai2008-04-23
| | | | | | | | | | | | | | | | | | [mszeredi@suse.cz] split big patch into managable chunks Add the following functions: dentry_path() seq_dentry() These are similar to d_path() and seq_path(). But instead of calculating the path within a mount namespace, they calculate the path from the root of the filesystem to a given dentry, ignoring mounts completely. Signed-off-by: Ram Pai <linuxram@us.ibm.com> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* dentries: Extract common code to remove dentry from lruChristoph Lameter2008-02-15
| | | | | | | | | | | | | | Extract the common code to remove a dentry from the lru into a new function dentry_lru_remove(). Two call sites used list_del() instead of list_del_init(). AFAIK the performance of both is the same. dentry_lru_remove() does a list_del_init(). As a result dentry->d_lru is now always empty when a dentry is freed. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* d_path: Make d_path() use a struct pathJan Blunck2008-02-15
| | | | | | | | | | | | | | | | d_path() is used on a <dentry,vfsmount> pair. Lets use a struct path to reflect this. [akpm@linux-foundation.org: fix build in mm/memory.c] Signed-off-by: Jan Blunck <jblunck@suse.de> Acked-by: Bryan Wu <bryan.wu@analog.com> Acked-by: Christoph Hellwig <hch@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: Neil Brown <neilb@suse.de> Cc: Michael Halcrow <mhalcrow@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* d_path: kerneldoc cleanupJan Blunck2008-02-15
| | | | | | | | | | | | Move and update d_path() kernel API documentation. Signed-off-by: Jan Blunck <jblunck@suse.de> Acked-by: Christoph Hellwig <hch@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: Neil Brown <neilb@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* One less parameter to __d_pathJan Blunck2008-02-15
| | | | | | | | | | | | | | | All callers to __d_path pass the dentry and vfsmount of a struct path to __d_path. Pass the struct path directly, instead. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Andreas Gruenbacher <agruen@suse.de> Signed-off-by: Jan Blunck <jblunck@suse.de> Acked-by: Christoph Hellwig <hch@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: Neil Brown <neilb@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Use struct path in fs_structJan Blunck2008-02-15
| | | | | | | | | | * Use struct path in fs_struct. Signed-off-by: Andreas Gruenbacher <agruen@suse.de> Signed-off-by: Jan Blunck <jblunck@suse.de> Acked-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* inotify: remove debug codeNick Piggin2008-02-06
| | | | | | | | | | | | | | | | | The inotify debugging code is supposed to verify that the DCACHE_INOTIFY_PARENT_WATCHED scalability optimisation does not result in notifications getting lost nor extra needless locking generated. Unfortunately there are also some races in the debugging code. And it isn't very good at finding problems anyway. So remove it for now. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Robert Love <rlove@google.com> Cc: John McCutchan <ttb@tentacle.dhs.org> Cc: Jan Kara <jack@ucw.cz> Cc: Yan Zheng <yanzheng@21cn.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fs: use hlist_unhashedAkinobu Mita2008-02-06
| | | | | | | | Use hlist_unhashed() instead of opencoded equivalent. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* dcache: don't expose uninitialized memory in /proc/<pid>/fd/<fd>J. Bruce Fields2007-10-22
| | | | | | | | | | | | | | | | | | Well, it's not especially important that target->d_iname get the contents of dentry->d_iname, but it's important that it get initialized with *something*, otherwise we're just exposing some random piece of memory to anyone who reads the link at /proc/<pid>/fd/<fd> for the deleted file, when it's still held open by someone. I've run a test program that copies a short (<36 character) name ontop of a long (>=36 character) name and see that the first time I run it, without this patch, I get unpredicatable results out of /proc/<pid>/fd/<fd>. Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] audit: watching subtreesAl Viro2007-10-21
| | | | | | | | | | | | | | | | | | | New kind of audit rule predicates: "object is visible in given subtree". The part that can be sanely implemented, that is. Limitations: * if you have hardlink from outside of tree, you'd better watch it too (or just watch the object itself, obviously) * if you mount something under a watched tree, tell audit that new chunk should be added to watched subtrees * if you umount something in a watched tree and it's still mounted elsewhere, you will get matches on events happening there. New command tells audit to recalculate the trees, trimming such sources of false positives. Note that it's _not_ about path - if something mounted in several places (multiple mount, bindings, different namespaces, etc.), the match does _not_ depend on which one we are using for access. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: use the predefined d_unhashed inline function insteadDenis Cheng2007-10-17
| | | | | | Signed-off-by: Denis Cheng <crquan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* shrink_dcache_sb speedupDenis V. Lunev2007-10-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | This patch makes shrink_dcache_sb consistent with dentry pruning policy. On the first pass we iterate over dentry unused list and prepare some dentries for removal. However, since the existing code moves evicted dentries to the beginning of the LRU it can happen that fresh dentries from other superblocks will be inserted *before* our dentries. This can result in significant slowdown of shrink_dcache_sb(). Moreover, for virtual filesystems like unionfs which can call dput() during dentries kill existing code results in O(n^2) complexity. We observed 2 minutes shrink_dcache_sb() with only 35000 dentries. To avoid this effects we propose to isolate sb dentries at the end of LRU list. Signed-off-by: Denis V. Lunev <den@openvz.org> Signed-off-by: Kirill Korotaev <dev@openvz.org> Signed-off-by: Andrey Mirkin <amirkin@openvz.org> Cc: Neil Brown <neilb@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* dcache: trivial comment fixJ. Bruce Fields2007-10-17
| | | | | | | | As it stands this comment is confusing, and not quite grammatical. Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* clean out unused code in dentry pruningMiklos Szeredi2007-10-17
| | | | | | | | | | It looks like in the end all pruners want parents removed. So remove unused code and function arguments. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fs: remove the unused mempages parameterDenis Cheng2007-10-17
| | | | | | | | | | | | | | | | Since the mempages parameter is actually not used, they should be removed. Now there is only files_init use the mempages parameter, files_init(mempages); but I don't think the adaptation to mempages in files_init is really useful; and if files_init also changed to the prototype void (*func)(void), the wrapper vfs_caches_init would also not need the mempages parameter. Signed-off-by: Denis Cheng <crquan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Group short-lived and reclaimable kernel allocationsMel Gorman2007-10-16
| | | | | | | | | | | | | | | | | | This patch marks a number of allocations that are either short-lived such as network buffers or are reclaimable such as inode allocations. When something like updatedb is called, long-lived and unmovable kernel allocations tend to be spread throughout the address space which increases fragmentation. This patch groups these allocations together as much as possible by adding a new MIGRATE_TYPE. The MIGRATE_RECLAIMABLE type is for allocations that can be reclaimed on demand, but not moved. i.e. they can be migrated by deleting them and re-reading the information from elsewhere. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: Andy Whitcroft <apw@shadowen.org> Cc: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: Remove slab destructors from kmem_cache_create().Paul Mundt2007-07-19
| | | | | | | | | | | | | | Slab destructors were no longer supported after Christoph's c59def9f222d44bb7e2f0a559f2906191a0862d7 change. They've been BUGs for both slab and slub, and slob never supported them either. This rips out support for the dtor pointer from kmem_cache_create() completely and fixes up every single callsite in the kernel (there were about 224, not including the slab allocator definitions themselves, or the documentation references). Signed-off-by: Paul Mundt <lethal@linux-sh.org>
* mm: clean up and kernelify shrinker registrationRusty Russell2007-07-17
| | | | | | | | | | | | | | | | | | | I can never remember what the function to register to receive VM pressure is called. I have to trace down from __alloc_pages() to find it. It's called "set_shrinker()", and it needs Your Help. 1) Don't hide struct shrinker. It contains no magic. 2) Don't allocate "struct shrinker". It's not helpful. 3) Call them "register_shrinker" and "unregister_shrinker". 4) Call the function "shrink" not "shrinker". 5) Reduce the 17 lines of waffly comments to 13, but document it properly. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: David Chinner <dgc@sgi.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* header cleaning: don't include smp_lock.h when not usedRandy Dunlap2007-05-08
| | | | | | | | | | | | Remove includes of <linux/smp_lock.h> where it is not used/needed. Suggested by Al Viro. Builds cleanly on x86_64, i386, alpha, ia64, powerpc, sparc, sparc64, and arm (all 59 defconfigs). Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* VFS: delay the dentry name generation on sockets and pipesEric Dumazet2007-05-08
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 1) Introduces a new method in 'struct dentry_operations'. This method called d_dname() might be called from d_path() to build a pathname for special filesystems. It is called without locks. Future patches (if we succeed in having one common dentry for all pipes/sockets) may need to change prototype of this method, but we now use : char *d_dname(struct dentry *dentry, char *buffer, int buflen); 2) Adds a dynamic_dname() helper function that eases d_dname() implementations 3) Defines d_dname method for sockets : No more sprintf() at socket creation. This is delayed up to the moment someone does an access to /proc/pid/fd/... 4) Defines d_dname method for pipes : No more sprintf() at pipe creation. This is delayed up to the moment someone does an access to /proc/pid/fd/... A benchmark consisting of 1.000.000 calls to pipe()/close()/close() gives a *nice* speedup on my Pentium(M) 1.6 Ghz : 3.090 s instead of 3.450 s Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Acked-by: Christoph Hellwig <hch@infradead.org> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: shrink parent dentries when shrinking slabAndrew Morton2007-05-08
| | | | | | | | | | | | | | | | Teach the dentry slab shrinker to aggressively shrink parent dentries when shrinking the dentry cache. This is done to attempt to improve the situation where the dentry slab cache gets a lot of internal fragmentation due to pages containing directory dentries. It is expected that this change will cause some of those dentries to be reaped earlier, and with less scanning. Needs careful testing. Cc: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fix quadratic behavior of shrink_dcache_parent()Miklos Szeredi2007-05-08
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The time shrink_dcache_parent() takes, grows quadratically with the depth of the tree under 'parent'. This starts to get noticable at about 10,000. These kinds of depths don't occur normally, and filesystems which invoke shrink_dcache_parent() via d_invalidate() seem to have other depth dependent timings, so it's not even easy to expose this problem. However with FUSE it's easy to create a deep tree and d_invalidate() will also get called. This can make a syscall hang for a very long time. This is the original discovery of the problem by Russ Cox: http://article.gmane.org/gmane.comp.file-systems.fuse.devel/3826 The following patch fixes the quadratic behavior, by optionally allowing prune_dcache() to prune ancestors of a dentry in one go, instead of doing it one at a time. Common code in dput() and prune_one_dentry() is extracted into a new helper function d_kill(). shrink_dcache_parent() as well as shrink_dcache_sb() are converted to use the ancestry-pruner option. Only for shrink_dcache_memory() is this behavior not desirable, so it keeps using the old algorithm. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Maneesh Soni <maneesh@in.ibm.com> Acked-by: "Paul E. McKenney" <paulmck@us.ibm.com> Cc: Dipankar Sarma <dipankar@in.ibm.com> Cc: Neil Brown <neilb@suse.de> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* KMEM_CACHE(): simplify slab cache creationChristoph Lameter2007-05-07
| | | | | | | | | | | | | | | | | | | | | | | | | | | This patch provides a new macro KMEM_CACHE(<struct>, <flags>) to simplify slab creation. KMEM_CACHE creates a slab with the name of the struct, with the size of the struct and with the alignment of the struct. Additional slab flags may be specified if necessary. Example struct test_slab { int a,b,c; struct list_head; } __cacheline_aligned_in_smp; test_slab_cache = KMEM_CACHE(test_slab, SLAB_PANIC) will create a new slab named "test_slab" of the size sizeof(struct test_slab) and aligned to the alignment of test slab. If it fails then we panic. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Revert "[PATCH] Fix d_path for lazy unmounts"Linus Torvalds2007-02-13
| | | | | | | | | | | | | | | | | This reverts commit eb3dfb0cb1f4a44e2d0553f89514ce9f2a9fcaf1. It causes some strange Gnome problem with dbus-daemon getting stuck, so we'll revert it until that problem is understood. Reported by both walt and Greg KH, who both independently git-bisected the problem to this commit. Andreas is looking at it. Reported-by: walt <wa1ter@myrealbox.com> Reported-by: Greg KH <greg@kroah.com> Acked-by: Andreas Gruenbacher <agruen@suse.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] Fix d_path for lazy unmountsAndreas Gruenbacher2007-02-12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Here is a bugfix to d_path. First, when d_path() hits a lazily unmounted mount point, it tries to prepend the name of the lazily unmounted dentry to the path name. It gets this wrong, and also overwrites the slash that separates the name from the following pathname component. This is demonstrated by the attached test case, which prints "getcwd returned d_path-bugsubdir" with the bug. The correct result would be "getcwd returned d_path-bug/subdir". It could be argued that the name of the root dentry should not be part of the result of d_path in the first place. On the other hand, what the unconnected namespace was once reachable as may provide some useful hints to users, and so that seems okay. Second, it isn't always possible to tell from the __d_path result whether the specified root and rootmnt (i.e., the chroot) was reached: lazy unmounts of bind mounts will produce a path that does start with a non-slash so we can tell from that, but other lazy unmounts will produce a path that starts with a slash, just like "ordinary" paths. The attached patch cleans up __d_path() to fix the bug with overlapping pathname components. It also adds a @fail_deleted argument, which allows to get rid of some of the mess in sys_getcwd(). Grabbing the dcache_lock can then also be moved into __d_path(). The patch also makes sure that paths will only start with a slash for paths which are connected to the root and rootmnt. The @fail_deleted argument could be added to d_path() as well: this would allow callers to recognize deleted files, without having to resort to the ambiguous check for the " (deleted)" string at the end of the pathnames. This is not currently done, but it might be worthwhile. Signed-off-by: Andreas Gruenbacher <agruen@suse.de> Cc: Neil Brown <neilb@suse.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] dcache: avoid RCU for never-hashed dentriesEric Dumazet2006-12-07
| | | | | | | | | | | | | | | | | | | | | | Some dentries don't need to be globally visible in dentry hashtable. (pipes & sockets) Such dentries dont need to wait for a RCU grace period at delete time. Being able to free them permits a better CPU cache use (hot cache) This patch combined with (dont insert pipe dentries into dentry_hashtable) reduced time of { pipe(p); close(p[0]); close(p[1]);} on my UP machine (1.6 GHz Pentium-M) from 3.23 us to 2.86 us (But this patch does not depend on other patches, only bench results) Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Maneesh Soni <maneesh@in.ibm.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Cc: Dipankar Sarma <dipankar@in.ibm.com> Acked-by: David Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] slab: remove kmem_cache_tChristoph Lameter2006-12-07
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Replace all uses of kmem_cache_t with struct kmem_cache. The patch was generated using the following script: #!/bin/sh # # Replace one string by another in all the kernel sources. # set -e for file in `find * -name "*.c" -o -name "*.h"|xargs grep -l $1`; do quilt add $file sed -e "1,\$s/$1/$2/g" $file >/tmp/$$ mv /tmp/$$ $file quilt refresh done The script was run like this sh replace kmem_cache_t "struct kmem_cache" Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] VFS: Fix an error in unused dentry countingDavid Howells2006-10-28
| | | | | | | | | | | | | With Vasily Averin <vvs@sw.ru> Fix an error in unused dentry counting in shrink_dcache_for_umount_subtree() in which the count is modified without the dcache_lock held. Signed-off-by: David Howells <dhowells@redhat.com> Cc: Vasily Averin <vvs@sw.ru> Cc: Neil Brown <neilb@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] missing unused dentry in prune_dcache()?Vasily Averin2006-10-28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | On the the following patch: http://linux.bkbits.net:8080/linux-2.6/gnupatch@449b144ecSF1rYskg3q-SeR2vf88zg # ChangeSet # 2006/06/22 15:05:57-07:00 neilb@suse.de # [PATCH] Fix dcache race during umount # If prune_dcache finds a dentry that it cannot free, it leaves it where it # is (at the tail of the list) and exits, on the assumption that some other # thread will be removing that dentry soon. However as far as I see this comment is not correct: when we cannot take s_umount rw_semaphore (for example because it was taken in do_remount) this dentry is already extracted from dentry_unused list and we do not add it into the list again. Therefore dentry will not be found by prune_dcache() and shrink_dcache_sb() and will leave in memory very long time until the partition will be unmounted. The patch adds this dentry into tail of the dentry_unused list. Signed-off-by: Vasily Averin <vvs@sw.ru> Cc: Neil Brown <neilb@suse.de> Acked-by: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] VFS: Make d_materialise_unique() enforce directory uniquenessTrond Myklebust2006-10-21
| | | | | | | | | | | | | | | | | | | | | If the caller tries to instantiate a directory using an inode that already has a dentry alias, then we attempt to rename the existing dentry instead of instantiating a new one. Fail with an ELOOP error if the rename would affect one of our parent directories. This behaviour is needed in order to avoid issues such as http://bugzilla.kernel.org/show_bug.cgi?id=7178 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: Maneesh Soni <maneesh@in.ibm.com> Cc: Dipankar Sarma <dipankar@in.ibm.com> Cc: Neil Brown <neilb@cse.unsw.edu.au> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] VFS: Destroy the dentries contributed by a superblock on unmountingDavid Howells2006-10-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The attached patch destroys all the dentries attached to a superblock in one go by: (1) Destroying the tree rooted at s_root. (2) Destroying every entry in the anon list, one at a time. (3) Each entry in the anon list has its subtree consumed from the leaves inwards. This reduces the amount of work generic_shutdown_super() does, and avoids iterating through the dentry_unused list. Note that locking is almost entirely absent in the shrink_dcache_for_umount*() functions added by this patch. This is because: (1) at the point the filesystem calls generic_shutdown_super(), it is not permitted to further touch the superblock's set of dentries, and nor may it remove aliases from inodes; (2) the dcache memory shrinker now skips dentries that are being unmounted; and (3) the superblock no longer has any external references through which the VFS can reach it. Given these points, the only locking we need to do is when we remove dentries from the unused list and the name hashes, which we do a directory's worth at a time. We also don't need to guard against reference counts going to zero unexpectedly and removing bits of the tree we're working on as nothing else can call dput(). A cut down version of dentry_iput() has been folded into shrink_dcache_for_umount_subtree() function. Apart from not needing to unlock things, it also doesn't need to check for inotify watches. In this version of the patch, the complaint about a dentry still being in use has been expanded from a single BUG_ON() and now gives much more information. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: NeilBrown <neilb@suse.de> Acked-by: Ian Kent <raven@themaw.net> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] knfsd: close a race-opportunity in d_splice_aliasNeilBrown2006-10-04
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There is a possible race in d_splice_alias. Though __d_find_alias(inode, 1) will only return a dentry with DCACHE_DISCONNECTED set, it is possible for it to get cleared before the BUG_ON, and it is is not possible to lock against that. There are a couple of problems here. Firstly, the code doesn't match the comment. The comment describes a 'disconnected' dentry as being IS_ROOT as well as DCACHE_DISCONNECTED, however there is not testing of IS_ROOT anythere. A dentry is marked DCACHE_DISCONNECTED when allocated with d_alloc_anon, and remains DCACHE_DISCONNECTED while a path is built up towards the root. So a dentry can have a valid name and a valid parent and even grandparent, but will still be DCACHE_DISCONNECTED until a path to the root is created. Once the path to the root is complete, everything in the path gets DCACHE_DISCONNECTED cleared. So the fact that DCACHE_DISCONNECTED isn't enough to say that a dentry is free to be spliced in with a given name. This can only be allowed if the dentry does not yet have a name, so the IS_ROOT test is needed too. However even adding that test to __d_find_alias isn't enough. As d_splice_alias drops dcache_lock before calling d_move to perform the splice, it could race with another thread calling d_splice_alias to splice the inode in with a different name in a different part of the tree (in the case where a file has hard links). So that splicing code is only really safe for directories (as we know that directories only have one link). For directories, the caller of d_splice_alias will be holding i_mutex on the (unique) parent so there is no room for a race. A consequence of this is that a non-directory will never benefit from being spliced into a pre-exisiting dentry, but that isn't a problem. It is perfectly OK for a non-directory to have multiple dentries, some anonymous, some not. And the comment for d_splice_alias says that it only happens for directories anyway. Signed-off-by: Neil Brown <neilb@suse.de> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Dipankar Sarma <dipankar@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] BLOCK: Move extern declarations out of fs/*.c into header files [try #6]David Howells2006-09-30
| | | | | | | | | | | Create a new header file, fs/internal.h, for common definitions local to the sources in the fs/ directory. Move extern definitions that should be in header files from fs/*.c to fs/internal.h or other main header files where they span directories. Signed-Off-By: David Howells <dhowells@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* NFS: Add dentry materialisation opDavid Howells2006-09-22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The attached patch adds a new directory cache management function that prepares a disconnected anonymous function to be connected into the dentry tree. The anonymous dentry is transferred the name and parentage from another dentry. The following changes were made in [try #2]: (*) d_materialise_dentry() now switches the parentage of the two nodes around correctly when one or other of them is self-referential. The following changes were made in [try #7]: (*) d_instantiate_unique() has had the interior part split out as function __d_instantiate_unique(). Callers of this latter function must be holding the appropriate locks. (*) _d_rehash() has been added as a wrapper around __d_rehash() to call it with the most obvious hash list (the one from the name). d_rehash() now calls _d_rehash(). (*) d_materialise_dentry() is now __d_materialise_dentry() and is static. (*) d_materialise_unique() added to perform the combination of d_find_alias(), d_materialise_dentry() and d_add_unique() that the NFS client was doing twice, all within a single dcache_lock critical section. This reduces the number of times two different spinlocks were being accessed. The following further changes were made: (*) Add the dentries onto their parents d_subdirs lists. Signed-Off-By: David Howells <dhowells@redhat.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
* [PATCH] lockdep: annotate dcacheIngo Molnar2006-07-03
| | | | | | | | | | Teach special (recursive) locking code to the lock validator. Has no effect on non-lockdep kernels. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] lockdep: locking init debugging improvementIngo Molnar2006-07-03
| | | | | | | | | | | | Locking init improvement: - introduce and use __SPIN_LOCK_UNLOCKED for array initializations, to pass in the name string of locks, used by debugging Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* Remove obsolete #include <linux/config.h>Jörn Engel2006-06-30
| | | | | Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de> Signed-off-by: Adrian Bunk <bunk@stusta.de>
* [PATCH] core: use list_move()Akinobu Mita2006-06-26
| | | | | | | | | | | This patch converts the combination of list_del(A) and list_add(A, B) to list_move(A, B). Cc: Greg Kroah-Hartman <gregkh@suse.de> Cc: Ram Pai <linuxram@us.ibm.com> Signed-off-by: Akinobu Mita <mita@miraclelinux.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] use list_add_tail() instead of list_add()Akinobu Mita2006-06-26
| | | | | | | | | | | | | | This patch converts list_add(A, B.prev) to list_add_tail(A, &B) for readability. Acked-by: Karsten Keil <kkeil@suse.de> Cc: Jan Harkes <jaharkes@cs.cmu.edu> Acked-by: Jan Kara <jack@suse.cz> AOLed-by: David Woodhouse <dwmw2@infradead.org> Cc: Sridhar Samudrala <sri@us.ibm.com> Signed-off-by: Akinobu Mita <mita@miraclelinux.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] remove unlikely(sb) in prune_dcacheHua Zhong2006-06-25
| | | | | | | | | | | | | | | | | likely profiling shows that the following is a miss. After boot: [+- ] Type | # True | # False | Function:Filename@Line +unlikely | 1074| 0 prune_dcache()@:fs/dcache.c@409 After a bonnie++ run: +unlikely | 66716| 19584 prune_dcache()@:fs/dcache.c@409 So remove it. Signed-off-by: Hua Zhong <hzhong@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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