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2014-06-12Merge branch 'for-linus' of ↵Linus Torvalds1-1/+3
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs updates from Al Viro: "This the bunch that sat in -next + lock_parent() fix. This is the minimal set; there's more pending stuff. In particular, I really hope to get acct.c fixes merged this cycle - we need that to deal sanely with delayed-mntput stuff. In the next pile, hopefully - that series is fairly short and localized (kernel/acct.c, fs/super.c and fs/namespace.c). In this pile: more iov_iter work. Most of prereqs for ->splice_write with sane locking order are there and Kent's dio rewrite would also fit nicely on top of this pile" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (70 commits) lock_parent: don't step on stale ->d_parent of all-but-freed one kill generic_file_splice_write() ceph: switch to iter_file_splice_write() shmem: switch to iter_file_splice_write() nfs: switch to iter_splice_write_file() fs/splice.c: remove unneeded exports ocfs2: switch to iter_file_splice_write() ->splice_write() via ->write_iter() bio_vec-backed iov_iter optimize copy_page_{to,from}_iter() bury generic_file_aio_{read,write} lustre: get rid of messing with iovecs ceph: switch to ->write_iter() ceph_sync_direct_write: stop poking into iov_iter guts ceph_sync_read: stop poking into iov_iter guts new helper: copy_page_from_iter() fuse: switch to ->write_iter() btrfs: switch to ->write_iter() ocfs2: switch to ->write_iter() xfs: switch to ->write_iter() ...
2014-06-12lock_parent: don't step on stale ->d_parent of all-but-freed oneAl Viro1-1/+3
Dentry that had been through (or into) __dentry_kill() might be seen by shrink_dentry_list(); that's normal, it'll be taken off the shrink list and freed if __dentry_kill() has already finished. The problem is, its ->d_parent might be pointing to already freed dentry, so lock_parent() needs to be careful. We need to check that dentry hasn't already gone into __dentry_kill() *and* grab rcu_read_lock() before dropping ->d_lock - the latter makes sure that whatever we see in ->d_parent after dropping ->d_lock it won't be freed until we drop rcu_read_lock(). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-06-07fs: convert use of typedef ctl_table to struct ctl_tableJoe Perches1-1/+1
This typedef is unnecessary and should just be removed. Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-05-31dcache: add missing lockdep annotationLinus Torvalds1-1/+1
lock_parent() very much on purpose does nested locking of dentries, and is careful to maintain the right order (lock parent first). But because it didn't annotate the nested locking order, lockdep thought it might be a deadlock on d_lock, and complained. Add the proper annotation for the inner locking of the child dentry to make lockdep happy. Introduced by commit 046b961b45f9 ("shrink_dentry_list(): take parent's ->d_lock earlier"). Reported-and-tested-by: Josh Boyer <jwboyer@fedoraproject.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-05-30dentry_kill() doesn't need the second argument nowAl Viro1-7/+4
it's 1 in the only remaining caller. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-30dealing with the rest of shrink_dentry_list() livelockAl Viro1-2/+20
We have the same problem with ->d_lock order in the inner loop, where we are dropping references to ancestors. Same solution, basically - instead of using dentry_kill() we use lock_parent() (introduced in the previous commit) to get that lock in a safe way, recheck ->d_count (in case if lock_parent() has ended up dropping and retaking ->d_lock and somebody managed to grab a reference during that window), trylock the inode->i_lock and use __dentry_kill() to do the rest. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-30shrink_dentry_list(): take parent's ->d_lock earlierAl Viro1-12/+41
The cause of livelocks there is that we are taking ->d_lock on dentry and its parent in the wrong order, forcing us to use trylock on the parent's one. d_walk() takes them in the right order, and unfortunately it's not hard to create a situation when shrink_dentry_list() can't make progress since trylock keeps failing, and shrink_dcache_parent() or check_submounts_and_drop() keeps calling d_walk() disrupting the very shrink_dentry_list() it's waiting for. Solution is straightforward - if that trylock fails, let's unlock the dentry itself and take locks in the right order. We need to stabilize ->d_parent without holding ->d_lock, but that's doable using RCU. And we'd better do that in the very beginning of the loop in shrink_dentry_list(), since the checks on refcount, etc. would need to be redone anyway. That deals with a half of the problem - killing dentries on the shrink list itself. Another one (dropping their parents) is in the next commit. locking parent is interesting - it would be easy to do rcu_read_lock(), lock whatever we think is a parent, lock dentry itself and check if the parent is still the right one. Except that we need to check that *before* locking the dentry, or we are risking taking ->d_lock out of order. Fortunately, once the D1 is locked, we can check if D2->d_parent is equal to D1 without the need to lock D2; D2->d_parent can start or stop pointing to D1 only under D1->d_lock, so taking D1->d_lock is enough. In other words, the right solution is rcu_read_lock/lock what looks like parent right now/check if it's still our parent/rcu_read_unlock/lock the child. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-29expand dentry_kill(dentry, 0) in shrink_dentry_list()Al Viro1-13/+17
Result will be massaged to saner shape in the next commits. It is ugly, no questions - the point of that one is to be a provably equivalent transformation (and it might be worth splitting a bit more). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-29split dentry_kill()Al Viro1-26/+36
... into trylocks and everything else. The latter (actual killing) is __dentry_kill(). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-28lift the "already marked killed" case into shrink_dentry_list()Al Viro1-6/+9
It can happen only when dentry_kill() is called with unlock_on_failure equal to 0 - other callers had dentry pinned until the moment they've got ->d_lock and DCACHE_DENTRY_KILLED is set only after lockref_mark_dead(). IOW, only one of three call sites of dentry_kill() might end up reaching that code. Just move it there. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-04dcache: don't need rcu in shrink_dentry_list()Miklos Szeredi1-23/+4
Since now the shrink list is private and nobody can free the dentry while it is on the shrink list, we can remove RCU protection from this. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-04more graceful recovery in umount_collect()Al Viro1-76/+25
Start with shrink_dcache_parent(), then scan what remains. First of all, BUG() is very much an overkill here; we are holding ->s_umount, and hitting BUG() means that a lot of interesting stuff will be hanging after that point (sync(2), for example). Moreover, in cases when there had been more than one leak, we'll be better off reporting all of them. And more than just the last component of pathname - %pd is there for just such uses... That was the last user of dentry_lru_del(), so kill it off... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-04don't remove from shrink list in select_collect()Al Viro1-21/+10
If we find something already on a shrink list, just increment data->found and do nothing else. Loops in shrink_dcache_parent() and check_submounts_and_drop() will do the right thing - everything we did put into our list will be evicted and if there had been nothing, but data->found got non-zero, well, we have somebody else shrinking those guys; just try again. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-01dentry_kill(): don't try to remove from shrink listAl Viro1-8/+19
If the victim in on the shrink list, don't remove it from there. If shrink_dentry_list() manages to remove it from the list before we are done - fine, we'll just free it as usual. If not - mark it with new flag (DCACHE_MAY_FREE) and leave it there. Eventually, shrink_dentry_list() will get to it, remove the sucker from shrink list and call dentry_kill(dentry, 0). Which is where we'll deal with freeing. Since now dentry_kill(dentry, 0) may happen after or during dentry_kill(dentry, 1), we need to recognize that (by seeing DCACHE_DENTRY_KILLED already set), unlock everything and either free the sucker (in case DCACHE_MAY_FREE has been set) or leave it for ongoing dentry_kill(dentry, 1) to deal with. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-01expand the call of dentry_lru_del() in dentry_kill()Al Viro1-1/+6
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-01new helper: dentry_free()Al Viro1-5/+10
The part of old d_free() that dealt with actual freeing of dentry. Taken out of dentry_kill() into a separate function. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-01fold try_prune_one_dentry()Al Viro1-50/+25
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-05-01fold d_kill() and d_free()Al Viro1-52/+24
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-04-19fix races between __d_instantiate() and checks of dentry flagsAl Viro1-2/+1
in non-lazy walk we need to be careful about dentry switching from negative to positive - both ->d_flags and ->d_inode are updated, and in some places we might see only one store. The cases where dentry has been obtained by dcache lookup with ->i_mutex held on parent are safe - ->d_lock and ->i_mutex provide all the barriers we need. However, there are several places where we run into trouble: * do_last() fetches ->d_inode, then checks ->d_flags and assumes that inode won't be NULL unless d_is_negative() is true. Race with e.g. creat() - we might have fetched the old value of ->d_inode (still NULL) and new value of ->d_flags (already not DCACHE_MISS_TYPE). Lin Ming has observed and reported the resulting oops. * a bunch of places checks ->d_inode for being non-NULL, then checks ->d_flags for "is it a symlink". Race with symlink(2) in case if our CPU sees ->d_inode update first - we see non-NULL there, but ->d_flags still contains DCACHE_MISS_TYPE instead of DCACHE_SYMLINK_TYPE. Result: false negative on "should we follow link here?", with subsequent unpleasantness. Cc: stable@vger.kernel.org # 3.13 and 3.14 need that one Reported-and-tested-by: Lin Ming <minggr@gmail.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-04-08Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linuxLinus Torvalds1-0/+1
Pull drm updates from Dave Airlie: "Highlights: - drm: Generic display port aux features, primary plane support, drm master management fixes, logging cleanups, enforced locking checks (instead of docs), documentation improvements, minor number handling cleanup, pseudofs for shared inodes. - ttm: add ability to allocate from both ends - i915: broadwell features, power domain and runtime pm, per-process address space infrastructure (not enabled) - msm: power management, hdmi audio support - nouveau: ongoing GPU fault recovery, initial maxwell support, random fixes - exynos: refactored driver to clean up a lot of abstraction, DP support moved into drm, LVDS bridge support added, parallel panel support - gma500: SGX MMU support, SGX irq handling, asle irq work fixes - radeon: video engine bringup, ring handling fixes, use dp aux helpers - vmwgfx: add rendernode support" * 'drm-next' of git://people.freedesktop.org/~airlied/linux: (849 commits) DRM: armada: fix corruption while loading cursors drm/dp_helper: don't return EPROTO for defers (v2) drm/bridge: export ptn3460_init function drm/exynos: remove MODULE_DEVICE_TABLE definitions ARM: dts: exynos4412-trats2: enable exynos/fimd node ARM: dts: exynos4210-trats: enable exynos/fimd node ARM: dts: exynos4412-trats2: add panel node ARM: dts: exynos4210-trats: add panel node ARM: dts: exynos4: add MIPI DSI Master node drm/panel: add S6E8AA0 driver ARM: dts: exynos4210-universal_c210: add proper panel node drm/panel: add ld9040 driver panel/ld9040: add DT bindings panel/s6e8aa0: add DT bindings drm/exynos: add DSIM driver exynos/dsim: add DT bindings drm/exynos: disallow fbdev initialization if no device is connected drm/mipi_dsi: create dsi devices only for nodes with reg property drm/mipi_dsi: add flags to DSI messages Skip intel_crt_init for Dell XPS 8700 ...
2014-04-01vfs: add cross-renameMiklos Szeredi1-9/+41
If flags contain RENAME_EXCHANGE then exchange source and destination files. There's no restriction on the type of the files; e.g. a directory can be exchanged with a symlink. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: J. Bruce Fields <bfields@redhat.com>
2014-03-31Merge tag 'v3.14' into drm-intel-next-queuedDaniel Vetter1-2/+2
Linux 3.14 The vt-d w/a merged late in 3.14-rc needs a bit of fine-tuning, hence backmerge. Conflicts: drivers/gpu/drm/i915/i915_gem_gtt.c drivers/gpu/drm/i915/intel_ddi.c drivers/gpu/drm/i915/intel_dp.c All trivial adjacent lines changed type conflicts, so trivial git doesn't even show them in the merg commit. Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2014-03-23make prepend_name() work correctly when called with negative *buflenAl Viro1-2/+2
In all callchains leading to prepend_name(), the value left in *buflen is eventually discarded unused if prepend_name() has returned a negative. So we are free to do what prepend() does, and subtract from *buflen *before* checking for underflow (which turns into checking the sign of subtraction result, of course). Cc: stable@vger.kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-03-16drm: add pseudo filesystem for shared inodesDavid Herrmann1-0/+1
Our current DRM design uses a single address_space for all users of the same DRM device. However, there is no way to create an anonymous address_space without an underlying inode. Therefore, we wait for the first ->open() callback on a registered char-dev and take-over the inode of the char-dev. This worked well so far, but has several drawbacks: - We screw with FS internals and rely on some non-obvious invariants like inode->i_mapping being the same as inode->i_data for char-devs. - We don't have any address_space prior to the first ->open() from user-space. This leads to ugly fallback code and we cannot allocate global objects early. As pointed out by Al-Viro, fs/anon_inode.c is *not* supposed to be used by drivers for anonymous inode-allocation. Therefore, this patch follows the proposed alternative solution and adds a pseudo filesystem mount-point to DRM. We can then allocate private inodes including a private address_space for each DRM device at initialization time. Note that we could use: sysfs_get_inode(sysfs_mnt->mnt_sb, drm_device->dev->kobj.sd); to get access to the underlying sysfs-inode of a "struct device" object. However, most of this information is currently hidden and it's not clear whether this address_space is suitable for driver access. Thus, unless linux allows anonymous address_space objects or driver-core provides a public inode per device, we're left with our own private internal mount point. Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
2014-01-26__dentry_path() fixesAl Viro1-3/+6
* we need to save the starting point for restarts * reject pathologically short buffers outright Spotted-by: Denys Vlasenko <dvlasenk@redhat.com> Spotted-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-01-26vfs: Remove second variable named error in __dentry_pathEric W. Biederman1-1/+0
In commit 232d2d60aa5469bb097f55728f65146bd49c1d25 Author: Waiman Long <Waiman.Long@hp.com> Date: Mon Sep 9 12:18:13 2013 -0400 dcache: Translating dentry into pathname without taking rename_lock The __dentry_path locking was changed and the variable error was intended to be moved outside of the loop. Unfortunately the inner declaration of error was not removed. Resulting in a version of __dentry_path that will never return an error. Remove the problematic inner declaration of error and allow __dentry_path to return errors once again. Cc: stable@vger.kernel.org Cc: Waiman Long <Waiman.Long@hp.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-01-18Merge branch 'for-linus' of ↵Linus Torvalds1-1/+6
git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace Pull namespace fixes from Eric Biederman: "This is a set of 3 regression fixes. This fixes /proc/mounts when using "ip netns add <netns>" to display the actual mount point. This fixes a regression in clone that broke lxc-attach. This fixes a regression in the permission checks for mounting /proc that made proc unmountable if binfmt_misc was in use. Oops. My apologies for sending this pull request so late. Al Viro gave interesting review comments about the d_path fix that I wanted to address in detail before I sent this pull request. Unfortunately a bad round of colds kept from addressing that in detail until today. The executive summary of the review was: Al: Is patching d_path really sufficient? The prepend_path, d_path, d_absolute_path, and __d_path family of functions is a really mess. Me: Yes, patching d_path is really sufficient. Yes, the code is mess. No it is not appropriate to rewrite all of d_path for a regression that has existed for entirely too long already, when a two line change will do" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: vfs: Fix a regression in mounting proc fork: Allow CLONE_PARENT after setns(CLONE_NEWPID) vfs: In d_path don't call d_dname on a mount point
2013-12-12dcache: allow word-at-a-time name hashing with big-endian CPUsWill Deacon1-1/+1
When explicitly hashing the end of a string with the word-at-a-time interface, we have to be careful which end of the word we pick up. On big-endian CPUs, the upper-bits will contain the data we're after, so ensure we generate our masks accordingly (and avoid hashing whatever random junk may have been sitting after the string). This patch adds a new dcache helper, bytemask_from_count, which creates a mask appropriate for the CPU endianness. Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-11-27vfs: In d_path don't call d_dname on a mount pointEric W. Biederman1-1/+6
Aditya Kali (adityakali@google.com) wrote: > Commit bf056bfa80596a5d14b26b17276a56a0dcb080e5: > "proc: Fix the namespace inode permission checks." converted > the namespace files into symlinks. The same commit changed > the way namespace bind mounts appear in /proc/mounts: > $ mount --bind /proc/self/ns/ipc /mnt/ipc > Originally: > $ cat /proc/mounts | grep ipc > proc /mnt/ipc proc rw,nosuid,nodev,noexec 0 0 > > After commit bf056bfa80596a5d14b26b17276a56a0dcb080e5: > $ cat /proc/mounts | grep ipc > proc ipc:[4026531839] proc rw,nosuid,nodev,noexec 0 0 > > This breaks userspace which expects the 2nd field in > /proc/mounts to be a valid path. The symlink /proc/<pid>/ns/{ipc,mnt,net,pid,user,uts} point to dentries allocated with d_alloc_pseudo that we can mount, and that have interesting names printed out with d_dname. When these files are bind mounted /proc/mounts is not currently displaying the mount point correctly because d_dname is called instead of just displaying the path where the file is mounted. Solve this by adding an explicit check to distinguish mounted pseudo inodes and unmounted pseudo inodes. Unmounted pseudo inodes always use mount of their filesstem as the mnt_root in their path making these two cases easy to distinguish. CC: stable@vger.kernel.org Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Reported-by: Aditya Kali <adityakali@google.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2013-11-16fold try_to_ascend() into the sole remaining callerAl Viro1-31/+18
There used to be a bunch of tree-walkers in dcache.c, all alike. try_to_ascend() had been introduced to abstract a piece of logics duplicated in all of them. These days all these tree-walkers are implemented via the same iterator (d_walk()), which is the only remaining caller of try_to_ascend(), so let's fold it back... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-11-16dcache.c: get rid of pointless macrosAl Viro1-4/+2
D_HASH{MASK,BITS} are used once each, both in the same function (d_hash()). At this point they are actively misguiding - they imply that values are compiler constants, which is no longer true. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-11-16take read_seqbegin_or_lock() and friends to seqlock.hAl Viro1-29/+0
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-11-14Merge branch 'core-locking-for-linus' of ↵Linus Torvalds1-2/+2
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull core locking changes from Ingo Molnar: "The biggest changes: - add lockdep support for seqcount/seqlocks structures, this unearthed both bugs and required extra annotation. - move the various kernel locking primitives to the new kernel/locking/ directory" * 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (21 commits) block: Use u64_stats_init() to initialize seqcounts locking/lockdep: Mark __lockdep_count_forward_deps() as static lockdep/proc: Fix lock-time avg computation locking/doc: Update references to kernel/mutex.c ipv6: Fix possible ipv6 seqlock deadlock cpuset: Fix potential deadlock w/ set_mems_allowed seqcount: Add lockdep functionality to seqcount/seqlock structures net: Explicitly initialize u64_stats_sync structures for lockdep locking: Move the percpu-rwsem code to kernel/locking/ locking: Move the lglocks code to kernel/locking/ locking: Move the rwsem code to kernel/locking/ locking: Move the rtmutex code to kernel/locking/ locking: Move the semaphore core to kernel/locking/ locking: Move the spinlock code to kernel/locking/ locking: Move the lockdep code to kernel/locking/ locking: Move the mutex code to kernel/locking/ hung_task debugging: Add tracepoint to report the hang x86/locking/kconfig: Update paravirt spinlock Kconfig description lockstat: Report avg wait and hold times lockdep, x86/alternatives: Drop ancient lockdep fixup message ...
2013-11-13prepend_path() needs to reinitialize dentry/vfsmount/mnt on restartsAl Viro1-3/+6
... and equivalent is needed in 3.12; it's broken there as well Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-11-13fix unpaired rcu lock in prepend_path()Li Zhong1-0/+4
Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-11-13Merge branch 'for-linus' of ↵Linus Torvalds1-155/+187
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs updates from Al Viro: "All kinds of stuff this time around; some more notable parts: - RCU'd vfsmounts handling - new primitives for coredump handling - files_lock is gone - Bruce's delegations handling series - exportfs fixes plus misc stuff all over the place" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (101 commits) ecryptfs: ->f_op is never NULL locks: break delegations on any attribute modification locks: break delegations on link locks: break delegations on rename locks: helper functions for delegation breaking locks: break delegations on unlink namei: minor vfs_unlink cleanup locks: implement delegations locks: introduce new FL_DELEG lock flag vfs: take i_mutex on renamed file vfs: rename I_MUTEX_QUOTA now that it's not used for quotas vfs: don't use PARENT/CHILD lock classes for non-directories vfs: pull ext4's double-i_mutex-locking into common code exportfs: fix quadratic behavior in filehandle lookup exportfs: better variable name exportfs: move most of reconnect_path to helper function exportfs: eliminate unused "noprogress" counter exportfs: stop retrying once we race with rename/remove exportfs: clear DISCONNECTED on all parents sooner exportfs: more detailed comment for path_reconnect ...
2013-11-09dcache: don't clear DCACHE_DISCONNECTED too earlyJ. Bruce Fields1-1/+0
DCACHE_DISCONNECTED should not be cleared until we're sure the dentry is connected all the way up to the root of the filesystem. It *shouldn't* be cleared as soon as the dentry is connected to a parent. That will cause bugs at least on exportable filesystems. Acked-by: Christoph Hellwig <hch@infradead.org> Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-11-09dcache: Don't set DISCONNECTED on "pseudo filesystem" dentriesJ. Bruce Fields1-4/+9
I can't for the life of me see any reason why anyone should care whether a dentry that is never hooked into the dentry cache would need DCACHE_DISCONNECTED set. This originates from 4b936885ab04dc6e0bb0ef35e0e23c1a7364d9e5 "fs: improve scalability of pseudo filesystems", which probably just made the false assumption the DCACHE_DISCONNECTED was meant to be set on anything not connected to a parent somehow. So this is just confusing. Ideally the only uses of DCACHE_DISCONNECTED would be in the filehandle-lookup code, which needs it to ensure dentries are connected into the dentry tree before use. I left d_alloc_pseudo there even though it's now equivalent to __d_alloc(), just on the theory the name is better documentation of its intended use outside dcache.c. Cc: Nick Piggin <npiggin@kernel.dk> Acked-by: Christoph Hellwig <hch@infradead.org> Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-11-09dcache: use IS_ROOT to decide where dentry is hashedJ. Bruce Fields1-1/+6
Every hashed dentry is either hashed in the dentry_hashtable, or a superblock's s_anon list. __d_drop() assumes it can determine which is the case by checking DCACHE_DISCONNECTED; this is not true. It is true that when DCACHE_DISCONNECTED is cleared, the dentry is not only hashed on dentry_hashtable, but is fully connected to its parents back to the root. But the converse is *not* true: fs/exportfs/expfs.c:reconnect_path() attempts to connect a directory (found by filehandle lookup) back to root by ascending to parents and performing lookups one at a time. It does not clear DCACHE_DISCONNECTED until it's done, and that is not at all an atomic process. In particular, it is possible for DCACHE_DISCONNECTED to be set on a dentry which is hashed on the dentry_hashtable. Instead, use IS_ROOT() to check which hash chain a dentry is on. This *does* work: Dentries are hashed only by: - d_obtain_alias, which adds an IS_ROOT() dentry to sb_anon. - __d_rehash, called by _d_rehash: hashes to the dentry's parent, and all callers of _d_rehash appear to have d_parent set to a "real" parent. - __d_rehash, called by __d_move: rehashes the moved dentry to hash chain determined by target, and assigns target's d_parent to its d_parent, before dropping the dentry's d_lock. Therefore I believe it's safe for a holder of a dentry's d_lock to assume that it is hashed on sb_anon if and only if IS_ROOT(dentry) is true. I believe the incorrect assumption about DCACHE_DISCONNECTED was originally introduced by ceb5bdc2d246 "fs: dcache per-bucket dcache hash locking". Also add a comment while we're here. Cc: Nick Piggin <npiggin@kernel.dk> Acked-by: Christoph Hellwig <hch@infradead.org> Reviewed-by: NeilBrown <neilb@suse.de> Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-11-09VFS: Put a small type field into struct dentry::d_flagsDavid Howells1-5/+37
Put a type field into struct dentry::d_flags to indicate if the dentry is one of the following types that relate particularly to pathwalk: Miss (negative dentry) Directory "Automount" directory (defective - no i_op->lookup()) Symlink Other (regular, socket, fifo, device) The type field is set to one of the first five types on a dentry by calls to __d_instantiate() and d_obtain_alias() from information in the inode (if one is given). The type is cleared by dentry_unlink_inode() when it reconstitutes an existing dentry as a negative dentry. Accessors provided are: d_set_type(dentry, type) d_is_directory(dentry) d_is_autodir(dentry) d_is_symlink(dentry) d_is_file(dentry) d_is_negative(dentry) d_is_positive(dentry) A bunch of checks in pathname resolution switched to those. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-11-09fold __d_shrink() into its only remaining callerAl Viro1-22/+10
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-11-09RCU'd vfsmountsAl Viro1-6/+14
* RCU-delayed freeing of vfsmounts * vfsmount_lock replaced with a seqlock (mount_lock) * sequence number from mount_lock is stored in nameidata->m_seq and used when we exit RCU mode * new vfsmount flag - MNT_SYNC_UMOUNT. Set by umount_tree() when its caller knows that vfsmount will have no surviving references. * synchronize_rcu() done between unlocking namespace_sem in namespace_unlock() and doing pending mntput(). * new helper: legitimize_mnt(mnt, seq). Checks the mount_lock sequence number against seq, then grabs reference to mnt. Then it rechecks mount_lock again to close the race and either returns success or drops the reference it has acquired. The subtle point is that in case of MNT_SYNC_UMOUNT we can simply decrement the refcount and sod off - aforementioned synchronize_rcu() makes sure that final mntput() won't come until we leave RCU mode. We need that, since we don't want to end up with some lazy pathwalk racing with umount() and stealing the final mntput() from it - caller of umount() may expect it to return only once the fs is shut down and we don't want to break that. In other cases (i.e. with MNT_SYNC_UMOUNT absent) we have to do full-blown mntput() in case of mount_lock sequence number mismatch happening just as we'd grabbed the reference, but in those cases we won't be stealing the final mntput() from anything that would care. * mntput_no_expire() doesn't lock anything on the fast path now. Incidentally, SMP and UP cases are handled the same way - no ifdefs there. * normal pathname resolution does *not* do any writes to mount_lock. It does, of course, bump the refcounts of vfsmount and dentry in the very end, but that's it. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-11-09switch shrink_dcache_for_umount() to use of d_walk()Al Viro1-110/+85
we have too many iterators in fs/dcache.c... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-11-06seqcount: Add lockdep functionality to seqcount/seqlock structuresJohn Stultz1-2/+2
Currently seqlocks and seqcounts don't support lockdep. After running across a seqcount related deadlock in the timekeeping code, I used a less-refined and more focused variant of this patch to narrow down the cause of the issue. This is a first-pass attempt to properly enable lockdep functionality on seqlocks and seqcounts. Since seqcounts are used in the vdso gettimeofday code, I've provided non-lockdep accessors for those needs. I've also handled one case where there were nested seqlock writers and there may be more edge cases. Comments and feedback would be appreciated! Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Li Zefan <lizefan@huawei.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: netdev@vger.kernel.org Link: http://lkml.kernel.org/r/1381186321-4906-3-git-send-email-john.stultz@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-11-01vfs: decrapify dput(), fix cache behavior under normal loadLinus Torvalds1-2/+3
We do not want to dirty the dentry->d_flags cacheline in dput() just to set the DCACHE_REFERENCED flag when it is already set in the common case anyway. This way the first cacheline of the dentry (which contains the RCU lookup information etc) can stay shared among multiple CPU's. This finishes off some of the details of all the scalability patches merged during the merge window. Also don't mark dentry_kill() for inlining, since it's the uncommon path and inlining it just makes the common path slower due to extra function entry/exit overhead. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-10-25vfs: introduce d_instantiate_no_diralias()Miklos Szeredi1-0/+27
...which just returns -EBUSY if a directory alias would be created. This is to be used by fuse mkdir to make sure that a buggy or malicious userspace filesystem doesn't do anything nasty. Previously fuse used a private mutex for this purpose, which can now go away. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
2013-10-25move taking vfsmount_lock down into prepend_path()Al Viro1-9/+2
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-10-22vfs: fix new kernel-doc warningsRandy Dunlap1-8/+7
Move kernel-doc notation to immediately before its function to eliminate kernel-doc warnings introduced by commit db14fc3abcd5 ("vfs: add d_walk()") Warning(fs/dcache.c:1343): No description found for parameter 'data' Warning(fs/dcache.c:1343): No description found for parameter 'dentry' Warning(fs/dcache.c:1343): Excess function parameter 'parent' description in 'check_mount' Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Miklos Szeredi <mszeredi@suse.cz> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-15vfs: fix typo in comment in recent dentry workLinus Torvalds1-1/+1
Sedat points out that I transposed some letters in "LRU" and wrote "RLU" instead in one of the new comments explaining the flow. Let's just fix it. Reported-by: Sedat Dilek <sedat.dilek@jpberlin.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-14vfs: fix dentry LRU list handling and nr_dentry_unused accountingLinus Torvalds1-27/+101
The LRU list changes interacted badly with our nr_dentry_unused accounting, and even worse with the new DCACHE_LRU_LIST bit logic. This introduces helper functions to make sure everything follows the proper dcache d_lru list rules: the dentry cache is complicated by the fact that some of the hotpaths don't even want to look at the LRU list at all, and the fact that we use the same list entry in the dentry for both the LRU list and for our temporary shrinking lists when removing things from the LRU. The helper functions temporarily have some extra sanity checking for the flag bits that have to match the current LRU state of the dentry. We'll remove that before the final 3.12 release, but considering how easy it is to get wrong, this first cleanup version has some very particular sanity checking. Acked-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>