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* autofs: delete fs/autofs4 source filesIan Kent2018-06-081-632/+0
| | | | | | | | | | Delete the now unused autofs4 module files. Link: http://lkml.kernel.org/r/152626707391.28589.3553309771262313504.stgit@pluto.themaw.net Signed-off-by: Ian Kent <raven@themaw.net> 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>
* autofs4: use autofs instead of autofs4 everywhereIan Kent2018-06-081-66/+66
| | | | | | | | | | | Update naming within autofs source to be consistent by changing occurrences of autofs4 to autofs. Link: http://lkml.kernel.org/r/152626703688.28589.8315406711135226803.stgit@pluto.themaw.net Signed-off-by: Ian Kent <raven@themaw.net> 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>
* autofs - dont hold spin lock over direct mount expireIan Kent2016-12-041-7/+10
| | | | | | | | | | | | | | | | | | | | Commit 7cbdb4a286 altered the autofs indirect mount expire to not hold a spin lock during the expire check. The direct mount expire needs the same treatment because to make autofs expires namespace aware may_umount_tree() needs to to use a similar method to may_umount() when checking if a mount tree is in use. This means may_umount_tree() will end up taking the namespace_sem for the check so the autofs direct mount expire won't be allowed to hold a spin lock over the check. Signed-off-by: Ian Kent <raven@themaw.net> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Omar Sandoval <osandov@osandov.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* autofs - constify misc struct path instancesIan Kent2016-12-041-1/+1
| | | | | | | | Signed-off-by: Ian Kent <raven@themaw.net> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Omar Sandoval <osandov@osandov.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* autofs: change autofs4_wait() to take struct pathIan Kent2016-12-041-2/+3
| | | | | | | | | | | | | | | | In order to use the functions path_is_mountpoint() and path_has_submounts() autofs needs to pass a struct path in several places. Now change autofs4_wait() to take a struct path instead of a struct dentry. Link: http://lkml.kernel.org/r/20161011053413.27645.84666.stgit@pluto.themaw.net Signed-off-by: Ian Kent <raven@themaw.net> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Omar Sandoval <osandov@osandov.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* autofs: change autofs4_expire_wait()/do_expire_wait() to take struct pathIan Kent2016-12-041-1/+2
| | | | | | | | | | | | | | | | In order to use the functions path_is_mountpoint() and path_has_submounts() autofs needs to pass a struct path in several places. Start by changing autofs4_expire_wait() and do_expire_wait() to take a struct path instead of a struct dentry. Link: http://lkml.kernel.org/r/20161011053408.27645.40091.stgit@pluto.themaw.net Signed-off-by: Ian Kent <raven@themaw.net> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Omar Sandoval <osandov@osandov.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* autofs: use dentry flags to block walks during expireIan Kent2016-09-201-13/+42
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Somewhere along the way the autofs expire operation has changed to hold a spin lock over expired dentry selection. The autofs indirect mount expired dentry selection is complicated and quite lengthy so it isn't appropriate to hold a spin lock over the operation. Commit 47be61845c77 ("fs/dcache.c: avoid soft-lockup in dput()") added a might_sleep() to dput() causing a WARN_ONCE() about this usage to be issued. But the spin lock doesn't need to be held over this check, the autofs dentry info. flags are enough to block walks into dentrys during the expire. I've left the direct mount expire as it is (for now) because it is much simpler and quicker than the indirect mount expire and adding spin lock release and re-aquires would do nothing more than add overhead. Fixes: 47be61845c77 ("fs/dcache.c: avoid soft-lockup in dput()") Link: http://lkml.kernel.org/r/20160912014017.1773.73060.stgit@pluto.themaw.net Signed-off-by: Ian Kent <raven@themaw.net> Reported-by: Takashi Iwai <tiwai@suse.de> Tested-by: Takashi Iwai <tiwai@suse.de> Cc: Takashi Iwai <tiwai@suse.de> Cc: NeilBrown <neilb@suse.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* autofs racesAl Viro2016-06-121-19/+8
| | | | | | | | | | | | | * make autofs4_expire_indirect() skip the dentries being in process of expiry * do *not* mess with list_move(); making sure that dentry with AUTOFS_INF_EXPIRING are not picked for expiry is enough. * do not remove NO_RCU when we set EXPIRING, don't bother with smp_mb() there. Clear it at the same time we clear EXPIRING. Makes a bunch of tests simpler. * rename NO_RCU to WANT_EXPIRE, which is what it really is. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* autofs4: use pr_xxx() macros directly for loggingIan Kent2016-03-161-12/+12
| | | | | | | | | | Use the standard pr_xxx() log macros directly for log prints instead of the AUTOFS_XXX() macros. Signed-off-by: Ian Kent <ikent@redhat.com> Cc: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* autofs4: change log print macros to not insert newlineIan Kent2016-03-161-12/+12
| | | | | | | | | | | | | Common kernel coding practice is to include the newline of log prints within the log text rather than hidden away in a macro. To avoid introducing inconsistencies as changes are made change the log macros to not include the newline. Signed-off-by: Ian Kent <raven@themaw.net> Cc: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* autofs4: coding style fixesIan Kent2016-03-161-27/+33
| | | | | | | | | Try and make the coding style completely consistent throughtout the autofs module and inline with kernel coding style recommendations. Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* VFS: normal filesystems (and lustre): d_inode() annotationsDavid Howells2015-04-151-1/+1
| | | | | | | that's the bulk of filesystem drivers dealing with inodes of their own Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* VFS: (Scripted) Convert S_ISLNK/DIR/REG(dentry->d_inode) to d_is_*(dentry)David Howells2015-02-221-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Convert the following where appropriate: (1) S_ISLNK(dentry->d_inode) to d_is_symlink(dentry). (2) S_ISREG(dentry->d_inode) to d_is_reg(dentry). (3) S_ISDIR(dentry->d_inode) to d_is_dir(dentry). This is actually more complicated than it appears as some calls should be converted to d_can_lookup() instead. The difference is whether the directory in question is a real dir with a ->lookup op or whether it's a fake dir with a ->d_automount op. In some circumstances, we can subsume checks for dentry->d_inode not being NULL into this, provided we the code isn't in a filesystem that expects d_inode to be NULL if the dirent really *is* negative (ie. if we're going to use d_inode() rather than d_backing_inode() to get the inode pointer). Note that the dentry type field may be set to something other than DCACHE_MISS_TYPE when d_inode is NULL in the case of unionmount, where the VFS manages the fall-through from a negative dentry to a lower layer. In such a case, the dentry type of the negative union dentry is set to the same as the type of the lower dentry. However, if you know d_inode is not NULL at the call site, then you can use the d_is_xxx() functions even in a filesystem. There is one further complication: a 0,0 chardev dentry may be labelled DCACHE_WHITEOUT_TYPE rather than DCACHE_SPECIAL_TYPE. Strictly, this was intended for special directory entry types that don't have attached inodes. The following perl+coccinelle script was used: use strict; my @callers; open($fd, 'git grep -l \'S_IS[A-Z].*->d_inode\' |') || die "Can't grep for S_ISDIR and co. callers"; @callers = <$fd>; close($fd); unless (@callers) { print "No matches\n"; exit(0); } my @cocci = ( '@@', 'expression E;', '@@', '', '- S_ISLNK(E->d_inode->i_mode)', '+ d_is_symlink(E)', '', '@@', 'expression E;', '@@', '', '- S_ISDIR(E->d_inode->i_mode)', '+ d_is_dir(E)', '', '@@', 'expression E;', '@@', '', '- S_ISREG(E->d_inode->i_mode)', '+ d_is_reg(E)' ); my $coccifile = "tmp.sp.cocci"; open($fd, ">$coccifile") || die $coccifile; print($fd "$_\n") || die $coccifile foreach (@cocci); close($fd); foreach my $file (@callers) { chomp $file; print "Processing ", $file, "\n"; system("spatch", "--sp-file", $coccifile, $file, "--in-place", "--no-show-diff") == 0 || die "spatch failed"; } [AV: overlayfs parts skipped] Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* assorted conversions to %p[dD]Al Viro2014-11-191-20/+10
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* move d_rcu from overlapping d_child to overlapping d_aliasAl Viro2014-11-031-6/+6
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* autofs4: avoid taking fs_lock during rcu-walkNeilBrown2014-10-141-8/+38
| | | | | | | | | | | | | | | | | | | | | | | | | | | ->fs_lock protects AUTOFS_INF_EXPIRING. We need to be sure that once the flag is set, no new references beneath the dentry are taken. So rcu-walk currently needs to take fs_lock before checking the flag. This hurts performance. Change the expiry to a two-stage process. First set AUTOFS_INF_NO_RCU which forces any path walk into ref-walk mode, then drop the lock and call synchronize_rcu(). Once that returns we can be sure no rcu-walk is active beneath the dentry and we can check reference counts again. Now during an RCU-walk we can test AUTOFS_INF_EXPIRING without taking the lock as along as we test AUTOFS_INF_NO_RCU too. If either are set, we must abort the RCU-walk If neither are set, we know that refcounts will be tested again after we finish the RCU-walk so we are safe to continue. ->fs_lock is still taken in d_manage() to check for a non-trap directory. That will be resolved in the next patch. Signed-off-by: NeilBrown <neilb@suse.de> Reviewed-by: Ian Kent <raven@themaw.net> Tested-by: Ian Kent <raven@themaw.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* autofs4: make "autofs4_can_expire" idempotent.NeilBrown2014-10-141-6/+4
| | | | | | | | | | | | | | Have a "test" function change the value it is testing can be confusing, particularly as a future patch will be calling this function twice. So move the update for 'last_used' to avoid repeat expiry to the place where the final determination on what to expire is known. Signed-off-by: NeilBrown <neilb@suse.de> Reviewed-by: Ian Kent <raven@themaw.net> Tested-by: Ian Kent <raven@themaw.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* autofs4: factor should_expire() out of autofs4_expire_indirect.NeilBrown2014-10-141-74/+88
| | | | | | | | | | Future patch will potentially call this twice, so make it separate. Signed-off-by: NeilBrown <neilb@suse.de> Reviewed-by: Ian Kent <raven@themaw.net> Tested-by: Ian Kent <raven@themaw.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* autofs4: allow RCU-walk to walk through autofs4NeilBrown2014-10-141-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This series teaches autofs about RCU-walk so that we don't drop straight into REF-walk when we hit an autofs directory, and so that we avoid spinlocks as much as possible when performing an RCU-walk. This is needed so that the benefits of the recent NFS support for RCU-walk are fully available when NFS filesystems are automounted. Patches have been carefully reviewed and tested both with test suites and in production - thanks a lot to Ian Kent for his support there. This patch (of 6): Any attempt to look up a pathname that passes though an autofs4 mount is currently forced out of RCU-walk into REF-walk. This can significantly hurt performance of many-thread work loads on many-core systems, especially if the automounted filesystem supports RCU-walk but doesn't get to benefit from it. So if autofs4_d_manage is called with rcu_walk set, only fail with -ECHILD if it is necessary to wait longer than a spinlock. Signed-off-by: NeilBrown <neilb@suse.de> Reviewed-by: Ian Kent <raven@themaw.net> Tested-by: Ian Kent <raven@themaw.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* autofs - remove obsolete d_invalidate() from expireIan Kent2014-10-091-6/+0
| | | | | | | | | | | | | | | | | | | | | | | Biederman's umount-on-rmdir series changes d_invalidate() to sumarily remove mounts under the passed in dentry regardless of whether they are busy or not. So calling this in fs/autofs4/expire.c:autofs4_tree_busy() is definitely the wrong thing to do becuase it will silently umount entries instead of just cleaning stale dentrys. But this call shouldn't be needed and testing shows that automounting continues to function without it. As Al Viro correctly surmises the original intent of the call was to perform what shrink_dcache_parent() does. If at some time in the future I see stale dentries accumulating following failed mounts I'll revisit the issue and possibly add a shrink_dcache_parent() call if needed. Signed-off-by: Ian Kent <raven@themaw.net> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* autofs4: remove a redundant assignmentNeilBrown2014-08-091-1/+0
| | | | | | | | | | | | | | The variable 'ino' already exists and already has the correct value. The d_fsdata of a dentry is never changed after the d_fsdata is instantiated, so this new assignment cannot be necessary. It was introduced in commit b5b801779d59 ("autofs4: Add d_manage() dentry operation"). Signed-off-by: NeilBrown <neilb@suse.de> Acked-by: Ian Kent <raven@themaw.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* autofs: fix symlinks aren't checked for expiryIan Kent2014-01-241-0/+14
| | | | | | | | | | | | | | | | | | | | | | The autofs4 module doesn't consider symlinks for expire as it did in the older autofs v3 module (so it's actually a long standing regression). The user space daemon has focused on the use of bind mounts instead of symlinks for a long time now and that's why this has not been noticed. But with the future addition of amd map parsing to automount(8), not to mention amd itself (of am-utils), symlink expiry will be needed. The direct and offset mount types can't be symlinks and the tree mounts of version 4 were always real mounts so only indirect mounts need expire symlinks. Since the current users of the autofs4 module haven't reported this as a problem to date this patch probably isn't a candidate for backport to stable. Signed-off-by: Ian Kent <ikent@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* helper for reading ->d_countAl Viro2013-07-051-4/+4
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* autofs - remove autofs dentry mount checkDavid Jeffery2013-05-061-9/+0
| | | | | | | | | | | | | | | | | | | When checking if an autofs mount point is busy it isn't sufficient to only check if it's a mount point. For example, if the mount of an offset mountpoint in a tree is denied for this host by its export and the dentry becomes a process working directory the check incorrectly returns the mount as not in use at expire. This can happen since the default when mounting within a tree is nostrict, which means ingnore mount fails on mounts within the tree and continue. The nostrict option is meant to allow mounting in this case. Signed-off-by: David Jeffery <djeffery@redhat.com> Signed-off-by: Ian Kent <raven@themaw.net> Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* autofs4 - dont clear DCACHE_NEED_AUTOMOUNT on rootless mountIan Kent2012-12-141-9/+0
| | | | | | | | | | | | | | | The DCACHE_NEED_AUTOMOUNT flag is cleared on mount and set on expire for autofs rootless multi-mount dentrys to prevent unnecessary calls to ->d_automount(). Since DCACHE_MANAGE_TRANSIT is always set on autofs dentrys ->d_managed() is always called so the check can be done in ->d_manage() without the need to change the flag. This still avoids unnecessary calls to ->d_automount(), adds negligible overhead and eliminates a seriously ugly check in the expire code. Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* autofs4 - fix expire checkIan Kent2012-08-171-5/+0
| | | | | | | | | | | | | | | | | | | | | | In some cases when an autofs indirect mount is contained in a file system that is marked as shared (such as when systemd does the equivalent of "mount --make-rshared /" early in the boot), mounts stop expiring. When this happens the first expiry check on a mountpoint dentry in autofs_expire_indirect() sees a mountpoint dentry with a higher than minimal reference count. Consequently the dentry is condidered busy and the actual expiry check is never done. This particular check was originally meant as an optimisation to detect a path walk in progress but with the addition of rcu-walk it can be ineffective anyway. Removing the test allows automounts to expire again since the actual expire check doesn't rely on the dentry reference count. Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* autofs4 - fix get_next_positive_subdir()Ian Kent2012-08-161-18/+13
| | | | | | | | | | | | | | | | | | Following a report of a crash during an automount expire I found that the locking in fs/autofs4/expire.c:get_next_positive_subdir() was wrong. Not only is the locking wrong but the function is more complex than it needs to be. The function is meant to calculate (and dget) the next entry in the list of directories contained in the root of an autofs mount point (an autofs indirect mount to be precise). The main problem was that the d_lock of the owner of the list was not being taken when walking the list, which lead to list corruption under load. The only other lock that needs to be taken is against the next dentry candidate so it can be checked for usability. Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* autofs4 - fix lockdep splat in autofsSteven Rostedt2012-02-141-0/+2
| | | | | | | | | | | When recursing down the locks when traversing a tree/list in get_next_positive_dentry() or get_next_positive_subdir() a lock can change from being nested to being a parent which breaks lockdep. This patch tells lockdep about what we did. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Ian Kent <raven@themaw.net> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* autofs4 - remove autofs4_lockIan Kent2011-03-241-8/+10
| | | | | | | | | | The autofs4_lock introduced by the rcu-walk changes has unnecessarily broad scope. The locking is better handled by the per-autofs super block lookup_lock. Signed-off-by: Ian Kent <raven@themaw.net> Acked-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* autofs4 - fix autofs4_expire_indirect() traversalIan Kent2011-03-241-1/+51
| | | | | | | | | The vfs-scale changes changed the traversal used in autofs4_expire_indirect() from a list to a depth first tree traversal which isn't right. Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* autofs4 - fix dentry leak in autofs4_expire_direct()Ian Kent2011-03-241-4/+3
| | | | | | | | | There is a missing dput() when returning from autofs4_expire_direct() when we see that the dentry is already a pending mount. Signed-off-by: Ian Kent <raven@themaw.net> Acked-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* autofs4 - reinstate last used update on accessIan Kent2011-03-241-11/+2
| | | | | | | | | | | | | | When direct (and offset) mounts were introduced the the last used timeout could no longer be updated in ->d_revalidate(). This is because covered direct mounts would be followed over without calling the autofs file system. As a result the definition of the busyness check for all entries was changed to be "actually busy" being an open file or working directory within the automount. But now we have a call back in the follow so the last used update on any access can be re-instated. This requires DCACHE_MANAGE_TRANSIT to always be set. Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* autofs4 - fix get_next_positive_dentry()Ian Kent2011-01-181-2/+2
| | | | | | | | | | | | | | The initialization condition in fs/autofs4/expire.c:get_next_positive_dentry() appears to be incorrect. If prev == NULL I believe that root should be returned. Further down, at the current dentry check for it being simple_positive() it looks like the d_lock for dentry p should be dropped instead of dentry ret, otherwise when p is assinged to ret we end up with no lock on p and a lost lock on ret, which leads to a deadlock. Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* autofs4: Add d_manage() dentry operationIan Kent2011-01-161-25/+26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch required a previous patch to add the ->d_automount() dentry operation. Add a function to use the newly defined ->d_manage() dentry operation for blocking during mount and expire. Whether the VFS calls the dentry operations d_automount() and d_manage() is controled by the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags. autofs uses the d_automount() operation to callback to user space to request mount operations and the d_manage() operation to block walks into mounts that are under construction or destruction. In order to prevent these functions from being called unnecessarily the DMANAGED_* flags are cleared for cases which would cause this. In the common case the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags are both set for dentrys waiting to be mounted. The DMANAGED_TRANSIT flag is cleared upon successful mount request completion and set during expire runs, both during the dentry expire check, and if selected for expire, is left set until a subsequent successful mount request completes. The exception to this is the so-called rootless multi-mount which has no actual mount at its base. In this case the DMANAGED_AUTOMOUNT flag is cleared upon successful mount request completion as well and set again after a successful expire. Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* autofs4: Add d_automount() dentry operationIan Kent2011-01-161-0/+6
| | | | | | | | | | | | | | Add a function to use the newly defined ->d_automount() dentry operation for triggering mounts instead of doing the user space callback in ->lookup() and ->d_revalidate(). Note, to be useful the subsequent patch to add the ->d_manage() dentry operation is also needed so the discussion of functionality is deferred to that patch. Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* Add a dentry op to allow processes to be held during pathwalk transitDavid Howells2011-01-161-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* fs: dcache remove d_mountedNick Piggin2011-01-071-2/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Rather than keep a d_mounted count in the dentry, set a dentry flag instead. The flag can be cleared by checking the hash table to see if there are any mounts left, which is not time critical because it is performed at detach time. The mounted state of a dentry is only used to speculatively take a look in the mount hash table if it is set -- before following the mount, vfsmount lock is taken and mount re-checked without races. This saves 4 bytes on 32-bit, nothing on 64-bit but it does provide a hole I might use later (and some configs have larger than 32-bit spinlocks which might make use of the hole). Autofs4 conversion and changelog by Ian Kent <raven@themaw.net>: In autofs4, when expring direct (or offset) mounts we need to ensure that we block user path walks into the autofs mount, which is covered by another mount. To do this we clear the mounted status so that follows stop before walking into the mount and are essentially blocked until the expire is completed. The automount daemon still finds the correct dentry for the umount due to the follow mount logic in fs/autofs4/root.c:autofs4_follow_link(), which is set as an inode operation for direct and offset mounts only and is called following the lookup that stopped at the covered mount. At the end of the expire the covering mount probably has gone away so the mounted status need not be restored. But we need to check this and only restore the mounted status if the expire failed. XXX: autofs may not work right if we have other mounts go over the top of it? Signed-off-by: Nick Piggin <npiggin@kernel.dk>
* fs: dcache remove dcache_lockNick Piggin2011-01-071-5/+5
| | | | | | dcache_lock no longer protects anything. remove it. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
* fs: dcache scale subdirsNick Piggin2011-01-071-67/+60
| | | | | | | | | | | | Protect d_subdirs and d_child with d_lock, except in filesystems that aren't using dcache_lock for these anyway (eg. using i_mutex). Note: if we change the locking rule in future so that ->d_child protection is provided only with ->d_parent->d_lock, it may allow us to reduce some locking. But it would be an exception to an otherwise regular locking scheme, so we'd have to see some good results. Probably not worthwhile. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
* fs: dcache scale d_unhashedNick Piggin2011-01-071-5/+16
| | | | | | | Protect d_unhashed(dentry) condition with d_lock. This means keeping DCACHE_UNHASHED bit in synch with hash manipulations. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
* fs: dcache scale dentry refcountNick Piggin2011-01-071-4/+4
| | | | | | | | Make d_count non-atomic and protect it with d_lock. This allows us to ensure a 0 refcount dentry remains 0 without dcache_lock. It is also fairly natural when we start protecting many other dentry members with d_lock. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
* Revert "autofs4: always use lookup for lookup"Al Viro2010-03-031-5/+1
| | | | | | | | | | This reverts commit 213614d583748d00967a91cacd656f417efb36ce. Alas, ->d_revalidate() can't rely on ->lookup() finishing what it's started; if d_alloc() in do_lookup() fails, we are not going to call ->lookup() at all. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* autofs4: always use lookup for lookupIan Kent2009-12-161-1/+5
| | | | | | | | | | | | | | | | | We need to be able to cope with the directory mutex being held during ->d_revalidate() in some cases, but not all cases, and not necessarily by us. Because we need to release the mutex when we call back to the daemon to do perform a mount we must be sure that it is us who holds the mutex so we must redirect mount requests to ->lookup() if the mutex is held. Signed-off-by: Ian Kent <raven@themaw.net> Cc: Sage Weil <sage@newdream.net> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Andreas Dilger <adilger@sun.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Yehuda Saheh <yehuda@newdream.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* autofs4: use autofs_info for pending flagIan Kent2009-12-161-1/+1
| | | | | | | | | | | | | | | | Eliminate the use of the d_lock spin lock by using the autofs super block info spin lock. This reduces the number of spin locks we use by one and makes the code for the following patch (to redirect ->d_revalidate() to ->lookup()) a little simpler. Signed-off-by: Ian Kent <raven@themaw.net> Cc: Sage Weil <sage@newdream.net> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Andreas Dilger <adilger@sun.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Yehuda Saheh <yehuda@newdream.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* autofs4 - fix missed case when changing to use struct pathIan Kent2009-09-011-1/+1
| | | | | | | | | In the recent change by Al Viro that changes verious subsystems to use "struct path" one case was missed in the autofs4 module which causes mounts to no longer expire. Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* switch follow_down()Al Viro2009-06-121-8/+7
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* autofs4: fix incorrect return in autofs4_mount_busy()Ian Kent2009-05-031-1/+3
| | | | | | | | Fix an obvious incorrect return status in autofs4_mount_busy(). Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* autofs4: cleanup expire code duplicationIan Kent2009-04-011-10/+17
| | | | | | | | | | | A significant portion of the autofs_dev_ioctl_expire() and autofs4_expire_multi() functions is duplicated code. This patch cleans that up. Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* autofs4: make autofs type usage explicitIan Kent2009-01-071-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | - the type assigned at mount when no type is given is changed from 0 to AUTOFS_TYPE_INDIRECT. This was done because 0 and AUTOFS_TYPE_INDIRECT were being treated implicitly as the same type. - previously, an offset mount had it's type set to AUTOFS_TYPE_DIRECT|AUTOFS_TYPE_OFFSET but the mount control re-implementation needs to be able distinguish all three types. So this was changed to make the type setting explicit. - a type AUTOFS_TYPE_ANY was added for use by the re-implementation when checking if a given path is a mountpoint. It's not really a type as we use this to ask if a given path is a mountpoint in the autofs_dev_ioctl_ismountpoint() function. - functions to set and test the autofs mount types have been added to improve readability and make the type usage explicit. - the mount type is used from user space for the mount control re-implementtion so, for consistency, all the definitions have been moved to the user space include file include/linux/auto_fs4.h. Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* autofs4: correct offset mount expire checkIan Kent2008-11-071-4/+15
| | | | | | | | | | | | | When checking a directory tree in autofs_tree_busy() we can incorrectly decide that the tree isn't busy. This happens for the case of an active offset mount as autofs4_follow_mount() follows past the active offset mount, which has an open file handle used for expires, causing the file handle not to count toward the busyness check. Signed-off-by: Ian Kent <raven@themaw.net> Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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