path: root/Documentation/filesystems/vfs.txt
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2013-02-26vfs: kill FS_REVAL_DOT by adding a d_weak_revalidate dentry opJeff Layton
The following set of operations on a NFS client and server will cause server# mkdir a client# cd a server# mv a a.bak client# sleep 30 # (or whatever the dir attrcache timeout is) client# stat . stat: cannot stat `.': Stale NFS file handle Obviously, we should not be getting an ESTALE error back there since the inode still exists on the server. The problem is that the lookup code will call d_revalidate on the dentry that "." refers to, because NFS has FS_REVAL_DOT set. nfs_lookup_revalidate will see that the parent directory has changed and will try to reverify the dentry by redoing a LOOKUP. That of course fails, so the lookup code returns ESTALE. The problem here is that d_revalidate is really a bad fit for this case. What we really want to know at this point is whether the inode is still good or not, but we don't really care what name it goes by or whether the dcache is still valid. Add a new d_op->d_weak_revalidate operation and have complete_walk call that instead of d_revalidate. The intent there is to allow for a "weaker" d_revalidate that just checks to see whether the inode is still good. This is also gives us an opportunity to kill off the FS_REVAL_DOT special casing. [AV: changed method name, added note in porting, fixed confusion re having it possibly called from RCU mode (it won't be)] Cc: NeilBrown <neilb@suse.de> Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-12-20documentation: drop vmtruncateMarco Stornelli
Removed vmtruncate Signed-off-by: Marco Stornelli <marco.stornelli@gmail.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-08-04Documentation: get rid of write_superArtem Bityutskiy
The '->write_super' superblock method is gone, and this patch removes all the references to 'write_super' from various pieces of the kernel documentation. Cc: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-07-31mm: add support for a filesystem to activate swap files and use direct_IO ↵Mel Gorman
for writing swap pages Currently swapfiles are managed entirely by the core VM by using ->bmap to allocate space and write to the blocks directly. This effectively ensures that the underlying blocks are allocated and avoids the need for the swap subsystem to locate what physical blocks store offsets within a file. If the swap subsystem is to use the filesystem information to locate the blocks, it is critical that information such as block groups, block bitmaps and the block descriptor table that map the swap file were resident in memory. This patch adds address_space_operations that the VM can call when activating or deactivating swap backed by a file. int swap_activate(struct file *); int swap_deactivate(struct file *); The ->swap_activate() method is used to communicate to the file that the VM relies on it, and the address_space should take adequate measures such as reserving space in the underlying device, reserving memory for mempools and pinning information such as the block descriptor table in memory. The ->swap_deactivate() method is called on sys_swapoff() if ->swap_activate() returned success. After a successful swapfile ->swap_activate, the swapfile is marked SWP_FILE and swapper_space.a_ops will proxy to sis->swap_file->f_mappings->a_ops using ->direct_io to write swapcache pages and ->readpage to read. It is perfectly possible that direct_IO be used to read the swap pages but it is an unnecessary complication. Similarly, it is possible that ->writepage be used instead of direct_io to write the pages but filesystem developers have stated that calling writepage from the VM is undesirable for a variety of reasons and using direct_IO opens up the possibility of writing back batches of swap pages in the future. [a.p.zijlstra@chello.nl: Original patch] Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: David S. Miller <davem@davemloft.net> Cc: Eric B Munson <emunson@mgebm.net> Cc: Eric Paris <eparis@redhat.com> Cc: James Morris <jmorris@namei.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Christie <michaelc@cs.wisc.edu> Cc: Neil Brown <neilb@suse.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Cc: Xiaotian Feng <dfeng@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-07-14don't pass nameidata to ->create()Al Viro
boolean "does it have to be exclusive?" flag is passed instead; Local filesystem should just ignore it - the object is guaranteed not to be there yet. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-07-14stop passing nameidata to ->lookup()Al Viro
Just the flags; only NFS cares even about that, but there are legitimate uses for such argument. And getting rid of that completely would require splitting ->lookup() into a couple of methods (at least), so let's leave that alone for now... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-07-14stop passing nameidata * to ->d_revalidate()Al Viro
Just the lookup flags. Die, bastard, die... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-07-14kill struct opendataAl Viro
Just pass struct file *. Methods are happier that way... There's no need to return struct file * from finish_open() now, so let it return int. Next: saner prototypes for parts in namei.c Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-07-14make ->atomic_open() return intAl Viro
Change of calling conventions: old new NULL 1 file 0 ERR_PTR(-ve) -ve Caller *knows* that struct file *; no need to return it. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-07-14->atomic_open() prototype change - pass int * instead of bool *Al Viro
... and let finish_open() report having opened the file via that sucker. Next step: don't modify od->filp at all. [AV: FILE_CREATE was already used by cifs; Miklos' fix folded] Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-07-14vfs: add i_op->atomic_open()Miklos Szeredi
Add a new inode operation which is called on the last component of an open. Using this the filesystem can look up, possibly create and open the file in one atomic operation. If it cannot perform this (e.g. the file type turned out to be wrong) it may signal this by returning NULL instead of an open struct file pointer. i_op->atomic_open() is only called if the last component is negative or needs lookup. Handling cached positive dentries here doesn't add much value: these can be opened using f_op->open(). If the cached file turns out to be invalid, the open can be retried, this time using ->atomic_open() with a fresh dentry. For now leave the old way of using open intents in lookup and revalidate in place. This will be removed once all the users are converted. David Howells noticed that if ->atomic_open() opens the file but does not create it, handle_truncate() will be called on it even if it is not a regular file. Fix this by checking the file type in this case too. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-06-01Merge branch 'for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs changes from Al Viro. "A lot of misc stuff. The obvious groups: * Miklos' atomic_open series; kills the damn abuse of ->d_revalidate() by NFS, which was the major stumbling block for all work in that area. * ripping security_file_mmap() and dealing with deadlocks in the area; sanitizing the neighborhood of vm_mmap()/vm_munmap() in general. * ->encode_fh() switched to saner API; insane fake dentry in mm/cleancache.c gone. * assorted annotations in fs (endianness, __user) * parts of Artem's ->s_dirty work (jff2 and reiserfs parts) * ->update_time() work from Josef. * other bits and pieces all over the place. Normally it would've been in two or three pull requests, but signal.git stuff had eaten a lot of time during this cycle ;-/" Fix up trivial conflicts in Documentation/filesystems/vfs.txt (the 'truncate_range' inode method was removed by the VM changes, the VFS update adds an 'update_time()' method), and in fs/btrfs/ulist.[ch] (due to sparse fix added twice, with other changes nearby). * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (95 commits) nfs: don't open in ->d_revalidate vfs: retry last component if opening stale dentry vfs: nameidata_to_filp(): don't throw away file on error vfs: nameidata_to_filp(): inline __dentry_open() vfs: do_dentry_open(): don't put filp vfs: split __dentry_open() vfs: do_last() common post lookup vfs: do_last(): add audit_inode before open vfs: do_last(): only return EISDIR for O_CREAT vfs: do_last(): check LOOKUP_DIRECTORY vfs: do_last(): make ENOENT exit RCU safe vfs: make follow_link check RCU safe vfs: do_last(): use inode variable vfs: do_last(): inline walk_component() vfs: do_last(): make exit RCU safe vfs: split do_lookup() Btrfs: move over to use ->update_time fs: introduce inode operation ->update_time reiserfs: get rid of resierfs_sync_super reiserfs: mark the superblock as dirty a bit later ...
2012-06-01fs: introduce inode operation ->update_timeJosef Bacik
Btrfs has to make sure we have space to allocate new blocks in order to modify the inode, so updating time can fail. We've gotten around this by having our own file_update_time but this is kind of a pain, and Christoph has indicated he would like to make xfs do something different with atime updates. So introduce ->update_time, where we will deal with i_version an a/m/c time updates and indicate which changes need to be made. The normal version just does what it has always done, updates the time and marks the inode dirty, and then filesystems can choose to do something different. I've gone through all of the users of file_update_time and made them check for errors with the exception of the fault code since it's complicated and I wasn't quite sure what to do there, also Jan is going to be pushing the file time updates into page_mkwrite for those who have it so that should satisfy btrfs and make it not a big deal to check the file_update_time() return code in the generic fault path. Thanks, Signed-off-by: Josef Bacik <josef@redhat.com>
2012-05-29mm/fs: remove truncate_rangeHugh Dickins
Remove vmtruncate_range(), and remove the truncate_range method from struct inode_operations: only tmpfs ever supported it, and tmpfs has now converted over to using the fallocate method of file_operations. Update Documentation accordingly, adding (setlease and) fallocate lines. And while we're in mm.h, remove duplicate declarations of shmem_lock() and shmem_file_setup(): everyone is now using the ones in shmem_fs.h. Based-on-patch-by: Cong Wang <amwang@redhat.com> Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Cong Wang <amwang@redhat.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>
2012-04-09typo fix in Documentation/filesystems/vfs.txtAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-03-07Documentation: Fix multiple typo in DocumentationMasanari Iida
Signed-off-by: Masanari Iida <standby24x7@gmail.com> Acked-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2012-01-06vfs: switch ->show_options() to struct dentry *Al Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03switch ->mknod() to umode_tAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03switch ->create() to umode_tAl Viro
vfs_create() ignores everything outside of 16bit subset of its mode argument; switching it to umode_t is obviously equivalent and it's the only caller of the method Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03switch vfs_mkdir() and ->mkdir() to umode_tAl Viro
vfs_mkdir() gets int, but immediately drops everything that might not fit into umode_t and that's the only caller of ->mkdir()... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-09-27doc: fix broken referencesPaul Bolle
There are numerous broken references to Documentation files (in other Documentation files, in comments, etc.). These broken references are caused by typo's in the references, and by renames or removals of the Documentation files. Some broken references are simply odd. Fix these broken references, sometimes by dropping the irrelevant text they were part of. Signed-off-by: Paul Bolle <pebolle@tiscali.nl> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2011-07-25fs: take the ACL checks to common codeChristoph Hellwig
Replace the ->check_acl method with a ->get_acl method that simply reads an ACL from disk after having a cache miss. This means we can replace the ACL checking boilerplate code with a single implementation in namei.c. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-07-20fs: push i_mutex and filemap_write_and_wait down into ->fsync() handlersJosef Bacik
Btrfs needs to be able to control how filemap_write_and_wait_range() is called in fsync to make it less of a painful operation, so push down taking i_mutex and the calling of filemap_write_and_wait() down into the ->fsync() handlers. Some file systems can drop taking the i_mutex altogether it seems, like ext3 and ocfs2. For correctness sake I just pushed everything down in all cases to make sure that we keep the current behavior the same for everybody, and then each individual fs maintainer can make up their mind about what to do from there. Thanks, Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: Josef Bacik <josef@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-07-20vfs: increase shrinker batch sizeDave Chinner
Now that the per-sb shrinker is responsible for shrinking 2 or more caches, increase the batch size to keep econmies of scale for shrinking each cache. Increase the shrinker batch size to 1024 objects. To allow for a large increase in batch size, add a conditional reschedule to prune_icache_sb() so that we don't hold the LRU spin lock for too long. This mirrors the behaviour of the __shrink_dcache_sb(), and allows us to increase the batch size without needing to worry about problems caused by long lock hold times. To ensure that filesystems using the per-sb shrinker callouts don't cause problems, document that the object freeing method must reschedule appropriately inside loops. Signed-off-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-07-20superblock: add filesystem shrinker operationsDave Chinner
Now we have a per-superblock shrinker implementation, we can add a filesystem specific callout to it to allow filesystem internal caches to be shrunk by the superblock shrinker. Rather than perpetuate the multipurpose shrinker callback API (i.e. nr_to_scan == 0 meaning "tell me how many objects freeable in the cache), two operations will be added. The first will return the number of objects that are freeable, the second is the actual shrinker call. Signed-off-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-07-20->permission() sanitizing: don't pass flags to ->permission()Al Viro
not used by the instances anymore. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-07-20->permission() sanitizing: don't pass flags to ->check_acl()Al Viro
not used in the instances anymore. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-05-27fs: pass exact type of data dirties to ->dirty_inodeChristoph Hellwig
Tell the filesystem if we just updated timestamp (I_DIRTY_SYNC) or anything else, so that the filesystem can track internally if it needs to push out a transaction for fdatasync or not. This is just the prototype change with no user for it yet. I plan to push large XFS changes for the next merge window, and getting this trivial infrastructure in this window would help a lot to avoid tree interdependencies. Also remove incorrect comments that ->dirty_inode can't block. That has been changed a long time ago, and many implementations rely on it. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-03-31Fix common misspellingsLucas De Marchi
Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
2011-03-24fs: remove inode_lock from iput_final and prune_icacheDave Chinner
Now that inode state changes are protected by the inode->i_lock and the inode LRU manipulations by the inode_lru_lock, we can remove the inode_lock from prune_icache and the initial part of iput_final(). instead of using the inode_lock to protect the inode during iput_final, use the inode->i_lock instead. This protects the inode against new references being taken while we change the inode state to I_FREEING, as well as preventing prune_icache from grabbing the inode while we are manipulating it. Hence we no longer need the inode_lock in iput_final prior to setting I_FREEING on the inode. For prune_icache, we no longer need the inode_lock to protect the LRU list, and the inodes themselves are protected against freeing races by the inode->i_lock. Hence we can lift the inode_lock from prune_icache as well. Signed-off-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-03-18lose 'mounting_here' argument in ->d_manage()Al Viro
it's always false... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-03-16vfs: bury ->get_sb()Al Viro
This is an ex-parrot. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-01-15Unexport do_add_mount() and add in follow_automount(), not ->d_automount()David Howells
Unexport do_add_mount() and make ->d_automount() return the vfsmount to be added rather than calling do_add_mount() itself. follow_automount() will then do the addition. This slightly complicates things as ->d_automount() normally wants to add the new vfsmount to an expiration list and start an expiration timer. The problem with that is that the vfsmount will be deleted if it has a refcount of 1 and the timer will not repeat if the expiration list is empty. To this end, we require the vfsmount to be returned from d_automount() with a refcount of (at least) 2. One of these refs will be dropped unconditionally. In addition, follow_automount() must get a 3rd ref around the call to do_add_mount() lest it eat a ref and return an error, leaving the mount we have open to being expired as we would otherwise have only 1 ref on it. d_automount() should also add the the vfsmount to the expiration list (by calling mnt_set_expiry()) and start the expiration timer before returning, if this mechanism is to be used. The vfsmount will be unlinked from the expiration list by follow_automount() if do_add_mount() fails. This patch also fixes the call to do_add_mount() for AFS to propagate the mount flags from the parent vfsmount. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-01-15Allow d_manage() to be used in RCU-walk modeDavid Howells
Allow d_manage() to be called from pathwalk when it is in RCU-walk mode as well as when it is in Ref-walk mode. This permits __follow_mount_rcu() to call d_manage() directly. d_manage() needs a parameter to indicate that it is in RCU-walk mode as it isn't allowed to sleep if in that mode (but should return -ECHILD instead). autofs4_d_manage() can then be set to retain RCU-walk mode if the daemon accesses it and otherwise request dropping back to ref-walk mode. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-01-15Add a dentry op to allow processes to be held during pathwalk transitDavid Howells
Add a dentry op (d_manage) to permit a filesystem to hold a process and make it sleep when it tries to transit away from one of that filesystem's directories during a pathwalk. The operation is keyed off a new dentry flag (DCACHE_MANAGE_TRANSIT). The filesystem is allowed to be selective about which processes it holds and which it permits to continue on or prohibits from transiting from each flagged directory. This will allow autofs to hold up client processes whilst letting its userspace daemon through to maintain the directory or the stuff behind it or mounted upon it. The ->d_manage() dentry operation: int (*d_manage)(struct path *path, bool mounting_here); takes a pointer to the directory about to be transited away from and a flag indicating whether the transit is undertaken by do_add_mount() or do_move_mount() skipping through a pile of filesystems mounted on a mountpoint. It should return 0 if successful and to let the process continue on its way; -EISDIR to prohibit the caller from skipping to overmounted filesystems or automounting, and to use this directory; or some other error code to return to the user. ->d_manage() is called with namespace_sem writelocked if mounting_here is true and no other locks held, so it may sleep. However, if mounting_here is true, it may not initiate or wait for a mount or unmount upon the parameter directory, even if the act is actually performed by userspace. Within fs/namei.c, follow_managed() is extended to check with d_manage() first on each managed directory, before transiting away from it or attempting to automount upon it. follow_down() is renamed follow_down_one() and should only be used where the filesystem deliberately intends to avoid management steps (e.g. autofs). A new follow_down() is added that incorporates the loop done by all other callers of follow_down() (do_add/move_mount(), autofs and NFSD; whilst AFS, NFS and CIFS do use it, their use is removed by converting them to use d_automount()). The new follow_down() calls d_manage() as appropriate. It also takes an extra parameter to indicate if it is being called from mount code (with namespace_sem writelocked) which it passes to d_manage(). follow_down() ignores automount points so that it can be used to mount on them. __follow_mount_rcu() is made to abort rcu-walk mode if it hits a directory with DCACHE_MANAGE_TRANSIT set on the basis that we're probably going to have to sleep. It would be possible to enter d_manage() in rcu-walk mode too, and have that determine whether to abort or not itself. That would allow the autofs daemon to continue on in rcu-walk mode. Note that DCACHE_MANAGE_TRANSIT on a directory should be cleared when it isn't required as every tranist from that directory will cause d_manage() to be invoked. It can always be set again when necessary. ========================== WHAT THIS MEANS FOR AUTOFS ========================== Autofs currently uses the lookup() inode op and the d_revalidate() dentry op to trigger the automounting of indirect mounts, and both of these can be called with i_mutex held. autofs knows that the i_mutex will be held by the caller in lookup(), and so can drop it before invoking the daemon - but this isn't so for d_revalidate(), since the lock is only held on _some_ of the code paths that call it. This means that autofs can't risk dropping i_mutex from its d_revalidate() function before it calls the daemon. The bug could manifest itself as, for example, a process that's trying to validate an automount dentry that gets made to wait because that dentry is expired and needs cleaning up: mkdir S ffffffff8014e05a 0 32580 24956 Call Trace: [<ffffffff885371fd>] :autofs4:autofs4_wait+0x674/0x897 [<ffffffff80127f7d>] avc_has_perm+0x46/0x58 [<ffffffff8009fdcf>] autoremove_wake_function+0x0/0x2e [<ffffffff88537be6>] :autofs4:autofs4_expire_wait+0x41/0x6b [<ffffffff88535cfc>] :autofs4:autofs4_revalidate+0x91/0x149 [<ffffffff80036d96>] __lookup_hash+0xa0/0x12f [<ffffffff80057a2f>] lookup_create+0x46/0x80 [<ffffffff800e6e31>] sys_mkdirat+0x56/0xe4 versus the automount daemon which wants to remove that dentry, but can't because the normal process is holding the i_mutex lock: automount D ffffffff8014e05a 0 32581 1 32561 Call Trace: [<ffffffff80063c3f>] __mutex_lock_slowpath+0x60/0x9b [<ffffffff8000ccf1>] do_path_lookup+0x2ca/0x2f1 [<ffffffff80063c89>] .text.lock.mutex+0xf/0x14 [<ffffffff800e6d55>] do_rmdir+0x77/0xde [<ffffffff8005d229>] tracesys+0x71/0xe0 [<ffffffff8005d28d>] tracesys+0xd5/0xe0 which means that the system is deadlocked. This patch allows autofs to hold up normal processes whilst the daemon goes ahead and does things to the dentry tree behind the automouter point without risking a deadlock as almost no locks are held in d_manage() and none in d_automount(). Signed-off-by: David Howells <dhowells@redhat.com> Was-Acked-by: Ian Kent <raven@themaw.net> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-01-15Add a dentry op to handle automounting rather than abusing follow_link()David Howells
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: David Howells <dhowells@redhat.com> Was-Acked-by: Ian Kent <raven@themaw.net> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-01-14fs: small rcu-walk documentation fixesNick Piggin
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: provide rcu-walk aware permission i_opsNick Piggin
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: rcu-walk aware d_revalidate methodNick Piggin
Require filesystems be aware of .d_revalidate being called in rcu-walk mode (nd->flags & LOOKUP_RCU). For now do a simple push down, returning -ECHILD from all implementations. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: change d_hash for rcu-walkNick Piggin
Change d_hash so it may be called from lock-free RCU lookups. See similar patch for d_compare for details. For in-tree filesystems, this is just a mechanical change. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: change d_compare for rcu-walkNick Piggin
Change d_compare so it may be called from lock-free RCU lookups. This does put significant restrictions on what may be done from the callback, however there don't seem to have been any problems with in-tree fses. If some strange use case pops up that _really_ cannot cope with the rcu-walk rules, we can just add new rcu-unaware callbacks, which would cause name lookup to drop out of rcu-walk mode. For in-tree filesystems, this is just a mechanical change. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2011-01-07fs: change d_delete semanticsNick Piggin
Change d_delete from a dentry deletion notification to a dentry caching advise, more like ->drop_inode. Require it to be constant and idempotent, and not take d_lock. This is how all existing filesystems use the callback anyway. This makes fine grained dentry locking of dput and dentry lru scanning much simpler. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
2010-12-14Merge branch 'bugfixes' of git://git.linux-nfs.org/projects/trondmy/nfs-2.6Linus Torvalds
* 'bugfixes' of git://git.linux-nfs.org/projects/trondmy/nfs-2.6: NFS: Fix panic after nfs_umount() nfs: remove extraneous and problematic calls to nfs_clear_request nfs: kernel should return EPROTONOSUPPORT when not support NFSv4 NFS: Fix fcntl F_GETLK not reporting some conflicts nfs: Discard ACL cache on mode update NFS: Readdir cleanups NFS: nfs_readdir_search_for_cookie() don't mark as eof if cookie not found NFS: Fix a memory leak in nfs_readdir Call the filesystem back whenever a page is removed from the page cache NFS: Ensure we use the correct cookie in nfs_readdir_xdr_filler
2010-12-02Documentation/filesystems/vfs.txt: fix ->repeasepage() descriptionAndrew Morton
->releasepage() does not remove the page from the mapping. Acked-by: Neil Brown <neilb@suse.de> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-12-02Call the filesystem back whenever a page is removed from the page cacheLinus Torvalds
NFS needs to be able to release objects that are stored in the page cache once the page itself is no longer visible from the page cache. This patch adds a callback to the address space operations that allows filesystems to perform page cleanups once the page has been removed from the page cache. Original patch by: Linus Torvalds <torvalds@linux-foundation.org> [trondmy: cover the cases of invalidate_inode_pages2() and truncate_inode_pages()] Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2010-08-14bkl: Remove locked .ioctl file operationArnd Bergmann
The last user is gone, so we can safely remove this Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: John Kacur <jkacur@redhat.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2010-05-27fs: introduce new truncate sequencenpiggin@suse.de
Introduce a new truncate calling sequence into fs/mm subsystems. Rather than setattr > vmtruncate > truncate, have filesystems call their truncate sequence from ->setattr if filesystem specific operations are required. vmtruncate is deprecated, and truncate_pagecache and inode_newsize_ok helpers introduced previously should be used. simple_setattr is introduced for simple in-ram filesystems to implement the new truncate sequence. Eventually all filesystems should be converted to implement a setattr, and the default code in notify_change should go away. simple_setsize is also introduced to perform just the ATTR_SIZE portion of simple_setattr (ie. changing i_size and trimming pagecache). To implement the new truncate sequence: - filesystem specific manipulations (eg freeing blocks) must be done in the setattr method rather than ->truncate. - vmtruncate can not be used by core code to trim blocks past i_size in the event of write failure after allocation, so this must be performed in the fs code. - convert usage of helpers block_write_begin, nobh_write_begin, cont_write_begin, and *blockdev_direct_IO* to use _newtrunc postfixed variants. These avoid calling vmtruncate to trim blocks (see previous). - inode_setattr should not be used. generic_setattr is a new function to be used to copy simple attributes into the generic inode. - make use of the better opportunity to handle errors with the new sequence. Big problem with the previous calling sequence: the filesystem is not called until i_size has already changed. This means it is not allowed to fail the call, and also it does not know what the previous i_size was. Also, generic code calling vmtruncate to truncate allocated blocks in case of error had no good way to return a meaningful error (or, for example, atomically handle block deallocation). Cc: Christoph Hellwig <hch@lst.de> Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-05-27drop unused dentry argument to ->fsyncChristoph Hellwig
Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2010-04-23Documentation/: it's -> its where appropriateFrancis Galiegue
Fix obvious cases of "it's" being used when "its" was meant. Signed-off-by: Francis Galiegue <fgaliegue@gmail.com> Acked-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2009-12-10kill wait_on_page_writeback_rangeChristoph Hellwig
All callers really want the more logical filemap_fdatawait_range interface, so convert them to use it and merge wait_on_page_writeback_range into filemap_fdatawait_range. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jan Kara <jack@suse.cz>