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path: root/include/linux/dcache.h
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2008-12-31shrink struct dentryNick Piggin
struct dentry is one of the most critical structures in the kernel. So it's sad to see it going neglected. With CONFIG_PROFILING turned on (which is probably the common case at least for distros and kernel developers), sizeof(struct dcache) == 208 here (64-bit). This gives 19 objects per slab. I packed d_mounted into a hole, and took another 4 bytes off the inline name length to take the padding out from the end of the structure. This shinks it to 200 bytes. I could have gone the other way and increased the length to 40, but I'm aiming for a magic number, read on... I then got rid of the d_cookie pointer. This shrinks it to 192 bytes. Rant: why was this ever a good idea? The cookie system should increase its hash size or use a tree or something if lookups are a problem. Also the "fast dcookie lookups" in oprofile should be moved into the dcookie code -- how can oprofile possibly care about the dcookie_mutex? It gets dropped after get_dcookie() returns so it can't be providing any sort of protection. At 192 bytes, 21 objects fit into a 4K page, saving about 3MB on my system with ~140 000 entries allocated. 192 is also a multiple of 64, so we get nice cacheline alignment on 64 and 32 byte line systems -- any given dentry will now require 3 cachelines to touch all fields wheras previously it would require 4. I know the inline name size was chosen quite carefully, however with the reduction in cacheline footprint, it should actually be just about as fast to do a name lookup for a 36 character name as it was before the patch (and faster for other sizes). The memory footprint savings for names which are <= 32 or > 36 bytes long should more than make up for the memory cost for 33-36 byte names. Performance is a feature... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2008-10-23[PATCH vfs-2.6 2/6] vfs: add d_ancestor()OGAWA Hirofumi
This adds d_ancestor() instead of d_isparent(), then use it. If new_dentry == old_dentry, is_subdir() returns 1, looks strange. "new_dentry == old_dentry" is not subdir obviously. But I'm not checking callers for now, so this keeps current behavior. Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
2008-10-23[PATCH] kill d_alloc_anonChristoph Hellwig
Remove d_alloc_anon now that no users are left. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2008-10-23[PATCH] new helper: d_obtain_aliasChristoph Hellwig
The calling conventions of d_alloc_anon are rather unfortunate for all users, and it's name is not very descriptive either. Add d_obtain_alias as a new exported helper that drops the inode reference in the failure case, too and allows to pass-through NULL pointers and inodes to allow for tail-calls in the export operations. Incidentally this helper already existed as a private function in libfs.c as exportfs_d_alloc so kill that one and switch the callers to d_obtain_alias. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2008-08-25[PATCH] change d_add_ci argument orderingChristoph Hellwig
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>
2008-07-28dcache: Add case-insensitive support d_ci_add() routineBarry Naujok
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>
2008-07-11Merge branch 'linus' into core/rcuIngo Molnar
Conflicts: include/linux/rculist.h kernel/rcupreempt.c Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-23[patch 2/4] fs: make struct file arg to d_path constJan Engelhardt
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>
2008-05-19rcu: split list.h and move rcu-protected lists into rculist.hFranck Bui-Huu
Move rcu-protected lists from list.h into a new header file rculist.h. This is done because list are a very used primitive structure all over the kernel and it's currently impossible to include other header files in this list.h without creating some circular dependencies. For example, list.h implements rcu-protected list and uses rcu_dereference() without including rcupdate.h. It actually compiles because users of rcu_dereference() are macros. Others RCU functions could be used too but aren't probably because of this. Therefore this patch creates rculist.h which includes rcupdates without to many changes/troubles. Signed-off-by: Franck Bui-Huu <fbuihuu@gmail.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Josh Triplett <josh@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-30Remove "#ifdef __KERNEL__" checks from unexported headersRobert P. J. Day
Remove the "#ifdef __KERNEL__" tests from unexported header files in linux/include whose entire contents are wrapped in that preprocessor test. Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Sam Ravnborg <sam@ravnborg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-23[patch 2/7] vfs: mountinfo: add seq_file_root()Miklos Szeredi
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>
2008-04-23[patch 1/7] vfs: mountinfo: add dentry_path()Ram Pai
[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>
2008-04-21[PATCH] move a bunch of declarations to fs/internal.hAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2008-02-14d_path: Make d_path() use a struct pathJan Blunck
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>
2007-10-21[PATCH] audit: watching subtreesAl Viro
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>
2007-05-08VFS: delay the dentry name generation on sockets and pipesEric Dumazet
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>
2006-10-11[PATCH] VFS: Destroy the dentries contributed by a superblock on unmountingDavid Howells
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>
2006-09-22NFS: Add dentry materialisation opDavid Howells
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>
2006-07-03[PATCH] lockdep: annotate dcacheIngo Molnar
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>
2006-06-23[PATCH] VFS: Permit filesystem to override root dentry on mountDavid Howells
Extend the get_sb() filesystem operation to take an extra argument that permits the VFS to pass in the target vfsmount that defines the mountpoint. The filesystem is then required to manually set the superblock and root dentry pointers. For most filesystems, this should be done with simple_set_mnt() which will set the superblock pointer and then set the root dentry to the superblock's s_root (as per the old default behaviour). The get_sb() op now returns an integer as there's now no need to return the superblock pointer. This patch permits a superblock to be implicitly shared amongst several mount points, such as can be done with NFS to avoid potential inode aliasing. In such a case, simple_set_mnt() would not be called, and instead the mnt_root and mnt_sb would be set directly. The patch also makes the following changes: (*) the get_sb_*() convenience functions in the core kernel now take a vfsmount pointer argument and return an integer, so most filesystems have to change very little. (*) If one of the convenience function is not used, then get_sb() should normally call simple_set_mnt() to instantiate the vfsmount. This will always return 0, and so can be tail-called from get_sb(). (*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the dcache upon superblock destruction rather than shrink_dcache_anon(). This is required because the superblock may now have multiple trees that aren't actually bound to s_root, but that still need to be cleaned up. The currently called functions assume that the whole tree is rooted at s_root, and that anonymous dentries are not the roots of trees which results in dentries being left unculled. However, with the way NFS superblock sharing are currently set to be implemented, these assumptions are violated: the root of the filesystem is simply a dummy dentry and inode (the real inode for '/' may well be inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries with child trees. [*] Anonymous until discovered from another tree. (*) The documentation has been adjusted, including the additional bit of changing ext2_* into foo_* in the documentation. [akpm@osdl.org: convert ipath_fs, do other stuff] Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Cc: Nathan Scott <nathans@sgi.com> Cc: Roland Dreier <rolandd@cisco.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-22[PATCH] Fix dcache race during umountNeilBrown
The race is that the shrink_dcache_memory shrinker could get called while a filesystem is being unmounted, and could try to prune a dentry belonging to that filesystem. If it does, then it will call in to iput on the inode while the dentry is no longer able to be found by the umounting process. If iput takes a while, generic_shutdown_super could get all the way though shrink_dcache_parent and shrink_dcache_anon and invalidate_inodes without ever waiting on this particular inode. Eventually the superblock gets freed anyway and if the iput tried to touch it (which some filesystems certainly do), it will lose. The promised "Self-destruct in 5 seconds" doesn't lead to a nice day. The race is closed by holding s_umount while calling prune_one_dentry on someone else's dentry. As a down_read_trylock is used, shrink_dcache_memory will no longer try to prune the dentry of a filesystem that is being unmounted, and unmount will not be able to start until any such active prune_one_dentry completes. This requires that prune_dcache *knows* which filesystem (if any) it is doing the prune on behalf of so that it can be careful of other filesystems. shrink_dcache_memory isn't called it on behalf of any filesystem, and so is careful of everything. shrink_dcache_anon is now passed a super_block rather than the s_anon list out of the superblock, so it can get the s_anon list itself, and can pass the superblock down to prune_dcache. 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. To try to make sure that some work gets done, a limited number of dnetries which are untouchable are skipped over while choosing the dentry to work on. I believe this race was first found by Kirill Korotaev. Cc: Jan Blunck <jblunck@suse.de> Acked-by: Kirill Korotaev <dev@openvz.org> Cc: Olaf Hering <olh@suse.de> Acked-by: Balbir Singh <balbir@in.ibm.com> Signed-off-by: Neil Brown <neilb@suse.de> Signed-off-by: Balbir Singh <balbir@in.ibm.com> Acked-by: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-31[PATCH] dcache: Add helper d_hash_and_lookupEric W. Biederman
It is very common to hash a dentry and then to call lookup. If we take fs specific hash functions into account the full hash logic can get ugly. Further full_name_hash as an inline function is almost 100 bytes on x86 so having a non-inline choice in some cases can measurably decrease code size. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-25[PATCH] inotify: lock avoidance with parent watch status in dentryNick Piggin
Previous inotify work avoidance is good when inotify is completely unused, but it breaks down if even a single watch is in place anywhere in the system. Robin Holt notices that udev is one such culprit - it slows down a 512-thread application on a 512 CPU system from 6 seconds to 22 minutes. Solve this by adding a flag in the dentry that tells inotify whether or not its parent inode has a watch on it. Event queueing to parent will skip taking locks if this flag is cleared. Setting and clearing of this flag on all child dentries versus event delivery: this is no in terms of race cases, and that was shown to be equivalent to always performing the check. The essential behaviour is that activity occuring _after_ a watch has been added and _before_ it has been removed, will generate events. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Robert Love <rml@novell.com> Cc: John McCutchan <ttb@tentacle.dhs.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-07[PATCH] remove bogus asm/bug.h includes.Al Viro
A bunch of asm/bug.h includes are both not needed (since it will get pulled anyway) and bogus (since they are done too early). Removed. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2006-02-03[PATCH] make "struct d_cookie" depend on CONFIG_PROFILINGMarcelo Tosatti
Shrinks "struct dentry" from 128 bytes to 124 on x86, allowing 31 objects per slab instead of 30. Cc: John Levon <levon@movementarian.org> Cc: Philippe Elie <phil.el@wanadoo.fr> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08[PATCH] shrink dentry structEric Dumazet
Some long time ago, dentry struct was carefully tuned so that on 32 bits UP, sizeof(struct dentry) was exactly 128, ie a power of 2, and a multiple of memory cache lines. Then RCU was added and dentry struct enlarged by two pointers, with nice results for SMP, but not so good on UP, because breaking the above tuning (128 + 8 = 136 bytes) This patch reverts this unwanted side effect, by using an union (d_u), where d_rcu and d_child are placed so that these two fields can share their memory needs. At the time d_free() is called (and d_rcu is really used), d_child is known to be empty and not touched by the dentry freeing. Lockless lookups only access d_name, d_parent, d_lock, d_op, d_flags (so the previous content of d_child is not needed if said dentry was unhashed but still accessed by a CPU because of RCU constraints) As dentry cache easily contains millions of entries, a size reduction is worth the extra complexity of the ugly C union. Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Cc: Dipankar Sarma <dipankar@in.ibm.com> Cc: Maneesh Soni <maneesh@in.ibm.com> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Cc: Ian Kent <raven@themaw.net> Cc: Paul Jackson <pj@sgi.com> Cc: Al Viro <viro@ftp.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: Neil Brown <neilb@cse.unsw.edu.au> Cc: James Morris <jmorris@namei.org> Cc: Stephen Smalley <sds@epoch.ncsc.mil> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07[PATCH] shared mounts handling: umountRam Pai
An unmount of a mount creates a umount event on the parent. If the parent is a shared mount, it gets propagated to all mounts in the peer group. Signed-off-by: Ram Pai <linuxram@us.ibm.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-07[PATCH] struct dentry: place d_hash close to d_parent and d_name to speedup ↵Eric Dumazet
lookups dentry cache uses sophisticated RCU technology (and prefetching if available) but touches 2 cache lines per dentry during hlist lookup. This patch moves d_hash in the same cache line than d_parent and d_name fields so that : 1) One cache line is needed instead of two. 2) the hlist_for_each_rcu() prefetching has a chance to bring all the needed data in advance, not only the part that includes d_hash.next. I also changed one old comment that was wrong for 64bits. A further optimisation would be to separate dentry in two parts, one that is mostly read, and one writen (d_count/d_lock) to avoid false sharing on SMP/NUMA but this would need different field placement depending on 32bits or 64bits platform. Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-16Linux-2.6.12-rc2v2.6.12-rc2Linus Torvalds
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!