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* fs: move dcache sysctls to its own fileLuis Chamberlain2022-01-221-6/+31
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | kernel/sysctl.c is a kitchen sink where everyone leaves their dirty dishes, this makes it very difficult to maintain. To help with this maintenance let's start by moving sysctls to places where they actually belong. The proc sysctl maintainers do not want to know what sysctl knobs you wish to add for your own piece of code, we just care about the core logic. So move the dcache sysctl clutter out of kernel/sysctl.c. This is a small one-off entry, perhaps later we can simplify this representation, but for now we use the helpers we have. We won't know how we can simplify this further untl we're fully done with the cleanup. [arnd@arndb.de: avoid unused-function warning] Link: https://lkml.kernel.org/r/20211203190123.874239-2-arnd@kernel.org Link: https://lkml.kernel.org/r/20211129205548.605569-4-mcgrof@kernel.org Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Antti Palosaari <crope@iki.fi> Cc: Eric Biederman <ebiederm@xmission.com> Cc: Iurii Zaikin <yzaikin@google.com> Cc: "J. Bruce Fields" <bfields@fieldses.org> Cc: Jeff Layton <jlayton@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: Lukas Middendorf <kernel@tuxforce.de> Cc: Stephen Kitt <steve@sk2.org> Cc: Xiaoming Ni <nixiaoming@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* useful constants: struct qstr for ".."Al Viro2021-04-151-0/+2
| | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* fs: delete repeated words in commentsRandy Dunlap2021-02-241-2/+2
| | | | | | | | | | | | | Delete duplicate words in fs/*.c. The doubled words that are being dropped are: that, be, the, in, and, for Link: https://lkml.kernel.org/r/20201224052810.25315-1-rdunlap@infradead.org Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'work.audit' of ↵Linus Torvalds2021-02-221-0/+25
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull RCU-safe common_lsm_audit() from Al Viro: "Make common_lsm_audit() non-blocking and usable from RCU pathwalk context. We don't really need to grab/drop dentry in there - rcu_read_lock() is enough. There's a couple of followups using that to simplify the logics in selinux, but those hadn't soaked in -next yet, so they'll have to go in next window" * 'work.audit' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: make dump_common_audit_data() safe to be called from RCU pathwalk new helper: d_find_alias_rcu()
| * new helper: d_find_alias_rcu()Al Viro2021-01-161-0/+25
| | | | | | | | | | | | | | | | | | | | similar to d_find_alias(inode), except that * the caller must be holding rcu_read_lock() * inode must not be freed until matching rcu_read_unlock() * result is *NOT* pinned and can only be dereferenced until the matching rcu_read_unlock(). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | fs: fix kernel-doc markupsMauro Carvalho Chehab2021-01-211-31/+32
|/ | | | | | | | | | | | Two markups are at the wrong place. Kernel-doc only support having the comment just before the identifier. Also, some identifiers have different names between their prototypes and the kernel-doc markup. Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Link: https://lore.kernel.org/r/96b1e1b388600ab092331f6c4e88ff8e8779ce6c.1610610937.git.mchehab+huawei@kernel.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* fs: Kill DCACHE_DONTCACHE dentry even if DCACHE_REFERENCED is setHao Li2020-12-101-1/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If DCACHE_REFERENCED is set, fast_dput() will return true, and then retain_dentry() have no chance to check DCACHE_DONTCACHE. As a result, the dentry won't be killed and the corresponding inode can't be evicted. In the following example, the DAX policy can't take effects unless we do a drop_caches manually. # DCACHE_LRU_LIST will be set echo abcdefg > test.txt # DCACHE_REFERENCED will be set and DCACHE_DONTCACHE can't do anything xfs_io -c 'chattr +x' test.txt # Drop caches to make DAX changing take effects echo 2 > /proc/sys/vm/drop_caches What this patch does is preventing fast_dput() from returning true if DCACHE_DONTCACHE is set. Then retain_dentry() will detect the DCACHE_DONTCACHE and will return false. As a result, the dentry will be killed and the inode will be evicted. In this way, if we change per-file DAX policy, it will take effects automatically after this file is closed by all processes. I also add some comments to make the code more clear. Signed-off-by: Hao Li <lihao2018.fnst@cn.fujitsu.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Ira Weiny <ira.weiny@intel.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* vfs: Use sequence counter with associated spinlockAhmed S. Darwish2020-07-291-1/+1
| | | | | | | | | | | | | | | | | | | A sequence counter write side critical section must be protected by some form of locking to serialize writers. A plain seqcount_t does not contain the information of which lock must be held when entering a write side critical section. Use the new seqcount_spinlock_t data type, which allows to associate a spinlock with the sequence counter. This enables lockdep to verify that the spinlock used for writer serialization is held when the write side critical section is entered. If lockdep is disabled this lock association is compiled out and has neither storage size nor runtime overhead. Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20200720155530.1173732-19-a.darwish@linutronix.de
* Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextLinus Torvalds2020-06-031-1/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull networking updates from David Miller: 1) Allow setting bluetooth L2CAP modes via socket option, from Luiz Augusto von Dentz. 2) Add GSO partial support to igc, from Sasha Neftin. 3) Several cleanups and improvements to r8169 from Heiner Kallweit. 4) Add IF_OPER_TESTING link state and use it when ethtool triggers a device self-test. From Andrew Lunn. 5) Start moving away from custom driver versions, use the globally defined kernel version instead, from Leon Romanovsky. 6) Support GRO vis gro_cells in DSA layer, from Alexander Lobakin. 7) Allow hard IRQ deferral during NAPI, from Eric Dumazet. 8) Add sriov and vf support to hinic, from Luo bin. 9) Support Media Redundancy Protocol (MRP) in the bridging code, from Horatiu Vultur. 10) Support netmap in the nft_nat code, from Pablo Neira Ayuso. 11) Allow UDPv6 encapsulation of ESP in the ipsec code, from Sabrina Dubroca. Also add ipv6 support for espintcp. 12) Lots of ReST conversions of the networking documentation, from Mauro Carvalho Chehab. 13) Support configuration of ethtool rxnfc flows in bcmgenet driver, from Doug Berger. 14) Allow to dump cgroup id and filter by it in inet_diag code, from Dmitry Yakunin. 15) Add infrastructure to export netlink attribute policies to userspace, from Johannes Berg. 16) Several optimizations to sch_fq scheduler, from Eric Dumazet. 17) Fallback to the default qdisc if qdisc init fails because otherwise a packet scheduler init failure will make a device inoperative. From Jesper Dangaard Brouer. 18) Several RISCV bpf jit optimizations, from Luke Nelson. 19) Correct the return type of the ->ndo_start_xmit() method in several drivers, it's netdev_tx_t but many drivers were using 'int'. From Yunjian Wang. 20) Add an ethtool interface for PHY master/slave config, from Oleksij Rempel. 21) Add BPF iterators, from Yonghang Song. 22) Add cable test infrastructure, including ethool interfaces, from Andrew Lunn. Marvell PHY driver is the first to support this facility. 23) Remove zero-length arrays all over, from Gustavo A. R. Silva. 24) Calculate and maintain an explicit frame size in XDP, from Jesper Dangaard Brouer. 25) Add CAP_BPF, from Alexei Starovoitov. 26) Support terse dumps in the packet scheduler, from Vlad Buslov. 27) Support XDP_TX bulking in dpaa2 driver, from Ioana Ciornei. 28) Add devm_register_netdev(), from Bartosz Golaszewski. 29) Minimize qdisc resets, from Cong Wang. 30) Get rid of kernel_getsockopt and kernel_setsockopt in order to eliminate set_fs/get_fs calls. From Christoph Hellwig. * git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2517 commits) selftests: net: ip_defrag: ignore EPERM net_failover: fixed rollback in net_failover_open() Revert "tipc: Fix potential tipc_aead refcnt leak in tipc_crypto_rcv" Revert "tipc: Fix potential tipc_node refcnt leak in tipc_rcv" vmxnet3: allow rx flow hash ops only when rss is enabled hinic: add set_channels ethtool_ops support selftests/bpf: Add a default $(CXX) value tools/bpf: Don't use $(COMPILE.c) bpf, selftests: Use bpf_probe_read_kernel s390/bpf: Use bcr 0,%0 as tail call nop filler s390/bpf: Maintain 8-byte stack alignment selftests/bpf: Fix verifier test selftests/bpf: Fix sample_cnt shared between two threads bpf, selftests: Adapt cls_redirect to call csum_level helper bpf: Add csum_level helper for fixing up csum levels bpf: Fix up bpf_skb_adjust_room helper's skb csum setting sfc: add missing annotation for efx_ef10_try_update_nic_stats_vf() crypto/chtls: IPv6 support for inline TLS Crypto/chcr: Fixes a coccinile check error Crypto/chcr: Fixes compilations warnings ...
| * sysctl: pass kernel pointers to ->proc_handlerChristoph Hellwig2020-04-271-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Instead of having all the sysctl handlers deal with user pointers, which is rather hairy in terms of the BPF interaction, copy the input to and from userspace in common code. This also means that the strings are always NUL-terminated by the common code, making the API a little bit safer. As most handler just pass through the data to one of the common handlers a lot of the changes are mechnical. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | fs: Introduce DCACHE_DONTCACHEIra Weiny2020-05-131-0/+19
|/ | | | | | | | | | | | | | | | | DCACHE_DONTCACHE indicates a dentry should not be cached on final dput(). Also add a helper function to mark DCACHE_DONTCACHE on all dentries pointing to a specific inode when that inode is being set I_DONTCACHE. This facilitates dropping dentry references to inodes sooner which require eviction to swap S_DAX mode. Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Ira Weiny <ira.weiny@intel.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
* Merge branch 'work.misc' of ↵Linus Torvalds2019-12-081-1/+1
|\ | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull misc vfs cleanups from Al Viro: "No common topic, just three cleanups". * 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: make __d_alloc() static fs/namespace: add __user to open_tree and move_mount syscalls fs/fnctl: fix missing __user in fcntl_rw_hint()
| * make __d_alloc() staticAl Viro2019-10-251-1/+1
| | | | | | | | | | | | no users outside of fs/dcache.c Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfsLinus Torvalds2019-12-061-2/+4
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull vfs d_inode/d_flags memory ordering fixes from Al Viro: "Fallout from tree-wide audit for ->d_inode/->d_flags barriers use. Basically, the problem is that negative pinned dentries require careful treatment - unless ->d_lock is locked or parent is held at least shared, another thread can make them positive right under us. Most of the uses turned out to be safe - the main surprises as far as filesystems are concerned were - race in dget_parent() fastpath, that might end up with the caller observing the returned dentry _negative_, due to insufficient barriers. It is positive in memory, but we could end up seeing the wrong value of ->d_inode in CPU cache. Fixed. - manual checks that result of lookup_one_len_unlocked() is positive (and rejection of negatives). Again, insufficient barriers (we might end up with inconsistent observed values of ->d_inode and ->d_flags). Fixed by switching to a new primitive that does the checks itself and returns ERR_PTR(-ENOENT) instead of a negative dentry. That way we get rid of boilerplate converting negatives into ERR_PTR(-ENOENT) in the callers and have a single place to deal with the barrier-related mess - inside fs/namei.c rather than in every caller out there. The guts of pathname resolution *do* need to be careful - the race found by Ritesh is real, as well as several similar races. Fortunately, it turns out that we can take care of that with fairly local changes in there. The tree-wide audit had not been fun, and I hate the idea of repeating it. I think the right approach would be to annotate the places where we are _not_ guaranteed ->d_inode/->d_flags stability and have sparse catch regressions. But I'm still not sure what would be the least invasive way of doing that and it's clearly the next cycle fodder" * 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: fs/namei.c: fix missing barriers when checking positivity fix dget_parent() fastpath race new helper: lookup_positive_unlocked() fs/namei.c: pull positivity check into follow_managed()
| * | fs/namei.c: fix missing barriers when checking positivityAl Viro2019-11-151-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pinned negative dentries can, generally, be made positive by another thread. Conditions that prevent that are * ->d_lock on dentry in question * parent directory held at least shared * nobody else could have observed the address of dentry Most of the places working with those fall into one of those categories; however, d_lookup() and friends need to be used with some care. Fortunately, there's not a lot of call sites, and with few exceptions all of those fall under one of the cases above. Exceptions are all in fs/namei.c - in lookup_fast(), lookup_dcache() and mountpoint_last(). Another one is lookup_slow() - there dcache lookup is done with parent held shared, but the result is used after we'd drop the lock. The same happens in do_last() - the lookup (in lookup_one()) is done with parent locked, but result is used after unlocking. lookup_fast(), do_last() and mountpoint_last() flat-out reject negatives. Most of lookup_dcache() calls are made with parent locked at least shared; the only exception is lookup_one_len_unlocked(). It might return pinned negative, needs serious care from callers. Fortunately, almost nobody calls it directly anymore; all but two callers have converted to lookup_positive_unlocked(), which rejects negatives. lookup_slow() is called by the same lookup_one_len_unlocked() (see above), mountpoint_last() and walk_component(). In those two negatives are rejected. In other words, there is a small set of places where we need to check carefully if a pinned potentially negative dentry is, in fact, positive. After that check we want to be sure that both ->d_inode and type bits in ->d_flags are stable and observed. The set consists of follow_managed() (where the rejection happens for lookup_fast(), walk_component() and do_last()), last_mountpoint() and lookup_positive_unlocked(). Solution: 1) transition from negative to positive (in __d_set_inode_and_type()) stores ->d_inode, then uses smp_store_release() to set ->d_flags type bits. 2) aforementioned 3 places in fs/namei.c fetch ->d_flags with smp_load_acquire() and bugger off if it type bits say "negative". That way anyone downstream of those checks has dentry know positive pinned, with ->d_inode and type bits of ->d_flags stable and observed. I considered splitting off d_lookup_positive(), so that the checks could be done right there, under ->d_lock. However, that leads to massive duplication of rather subtle code in fs/namei.c and fs/dcache.c. It's worse than it might seem, thanks to autofs ->d_manage() getting involved ;-/ No matter what, autofs_d_manage()/autofs_d_automount() must live with the possibility of pinned negative dentry passed their way, becoming positive under them - that's the intended behaviour when lookup comes in the middle of automount in progress, so we can't keep them out of the area that has to deal with those, more's the pity... Reported-by: Ritesh Harjani <riteshh@linux.ibm.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| * | fix dget_parent() fastpath raceAl Viro2019-11-151-1/+3
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We are overoptimistic about taking the fast path there; seeing the same value in ->d_parent after having grabbed a reference to that parent does *not* mean that it has remained our parent all along. That wouldn't be a big deal (in the end it is our parent and we have grabbed the reference we are about to return), but... the situation with barriers is messed up. We might have hit the following sequence: d is a dentry of /tmp/a/b CPU1: CPU2: parent = d->d_parent (i.e. dentry of /tmp/a) rename /tmp/a/b to /tmp/b rmdir /tmp/a, making its dentry negative grab reference to parent, end up with cached parent->d_inode (NULL) mkdir /tmp/a, rename /tmp/b to /tmp/a/b recheck d->d_parent, which is back to original decide that everything's fine and return the reference we'd got. The trouble is, caller (on CPU1) will observe dget_parent() returning an apparently negative dentry. It actually is positive, but CPU1 has stale ->d_inode cached. Use d->d_seq to see if it has been moved instead of rechecking ->d_parent. NOTE: we are *NOT* going to retry on any kind of ->d_seq mismatch; we just go into the slow path in such case. We don't wait for ->d_seq to become even either - again, if we are racing with renames, we can bloody well go to slow path anyway. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* / locking/lockdep: Remove unused @nested argument from lock_release()Qian Cai2019-10-091-1/+1
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since the following commit: b4adfe8e05f1 ("locking/lockdep: Remove unused argument in __lock_release") @nested is no longer used in lock_release(), so remove it from all lock_release() calls and friends. Signed-off-by: Qian Cai <cai@lca.pw> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Will Deacon <will@kernel.org> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: airlied@linux.ie Cc: akpm@linux-foundation.org Cc: alexander.levin@microsoft.com Cc: daniel@iogearbox.net Cc: davem@davemloft.net Cc: dri-devel@lists.freedesktop.org Cc: duyuyang@gmail.com Cc: gregkh@linuxfoundation.org Cc: hannes@cmpxchg.org Cc: intel-gfx@lists.freedesktop.org Cc: jack@suse.com Cc: jlbec@evilplan.or Cc: joonas.lahtinen@linux.intel.com Cc: joseph.qi@linux.alibaba.com Cc: jslaby@suse.com Cc: juri.lelli@redhat.com Cc: maarten.lankhorst@linux.intel.com Cc: mark@fasheh.com Cc: mhocko@kernel.org Cc: mripard@kernel.org Cc: ocfs2-devel@oss.oracle.com Cc: rodrigo.vivi@intel.com Cc: sean@poorly.run Cc: st@kernel.org Cc: tj@kernel.org Cc: tytso@mit.edu Cc: vdavydov.dev@gmail.com Cc: vincent.guittot@linaro.org Cc: viro@zeniv.linux.org.uk Link: https://lkml.kernel.org/r/1568909380-32199-1-git-send-email-cai@lca.pw Signed-off-by: Ingo Molnar <mingo@kernel.org>
* Merge branch 'work.dcache2' of ↵Linus Torvalds2019-07-201-17/+83
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull dcache and mountpoint updates from Al Viro: "Saner handling of refcounts to mountpoints. Transfer the counting reference from struct mount ->mnt_mountpoint over to struct mountpoint ->m_dentry. That allows us to get rid of the convoluted games with ordering of mount shutdowns. The cost is in teaching shrink_dcache_{parent,for_umount} to cope with mixed-filesystem shrink lists, which we'll also need for the Slab Movable Objects patchset" * 'work.dcache2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: switch the remnants of releasing the mountpoint away from fs_pin get rid of detach_mnt() make struct mountpoint bear the dentry reference to mountpoint, not struct mount Teach shrink_dcache_parent() to cope with mixed-filesystem shrink lists fs/namespace.c: shift put_mountpoint() to callers of unhash_mnt() __detach_mounts(): lookup_mountpoint() can't return ERR_PTR() anymore nfs: dget_parent() never returns NULL ceph: don't open-code the check for dead lockref
| * Teach shrink_dcache_parent() to cope with mixed-filesystem shrink listsAl Viro2019-07-101-17/+83
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, running into a shrink list that contains dentries from different filesystems can cause several unpleasant things for shrink_dcache_parent() and for umount(2). The first problem is that there's a window during shrink_dentry_list() between __dentry_kill() takes a victim out and dropping reference to its parent. During that window the parent looks like a genuine busy dentry. shrink_dcache_parent() (or, worse yet, shrink_dcache_for_umount()) coming at that time will see no eviction candidates and no indication that it needs to wait for some shrink_dentry_list() to proceed further. That applies for any shrink list that might intersect with the subtree we are trying to shrink; the only reason it does not blow on umount(2) in the mainline is that we unregister the memory shrinker before hitting shrink_dcache_for_umount(). Another problem happens if something in a mixed-filesystem shrink list gets be stuck in e.g. iput(), getting umount of unrelated fs to spin waiting for the stuck shrinker to get around to our dentries. Solution: 1) have shrink_dentry_list() decrement the parent's refcount and make sure it's on a shrink list (ours unless it already had been on some other) before calling __dentry_kill(). That eliminates the window when shrink_dcache_parent() would've blown past the entire subtree without noticing anything with zero refcount not on shrink lists. 2) when shrink_dcache_parent() has found no eviction candidates, but some dentries are still sitting on shrink lists, rather than repeating the scan in hope that shrinkers have progressed, scan looking for something on shrink lists with zero refcount. If such a thing is found, grab rcu_read_lock() and stop the scan, with caller locking it for eviction, dropping out of RCU and doing __dentry_kill(), with the same treatment for parent as shrink_dentry_list() would do. Note that right now mixed-filesystem shrink lists do not occur, so this is not a mainline bug. Howevere, there's a bunch of uses for such beasts (e.g. the "try and evict everything we can out of given page" patches; there are potential uses in mount-related code, considerably simplifying the life in fs/namespace.c, etc.) Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | fsnotify: move fsnotify_nameremove() hook out of d_delete()Amir Goldstein2019-06-201-2/+0
|/ | | | | | | | | | | | | | | | | | | | | d_delete() was piggy backed for the fsnotify_nameremove() hook when in fact not all callers of d_delete() care about fsnotify events. For all callers of d_delete() that may be interested in fsnotify events, we made sure to call one of fsnotify_{unlink,rmdir}() hooks before calling d_delete(). Now we can move the fsnotify_nameremove() call from d_delete() to the fsnotify_{unlink,rmdir}() hooks. Two explicit calls to fsnotify_nameremove() from nfs/afs sillyrename are also removed. This will cause a change of behavior - nfs/afs will NOT generate an fsnotify delete event when renaming over a positive dentry. This change is desirable, because it is consistent with the behavior of all other filesystems. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Jan Kara <jack@suse.cz>
* treewide: Add SPDX license identifier for missed filesThomas Gleixner2019-05-211-0/+1
| | | | | | | | | | | | | | | | | Add SPDX license identifiers to all files which: - Have no license information of any form - Have EXPORT_.*_SYMBOL_GPL inside which was used in the initial scan/conversion to ignore the file These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Merge tag 'fscrypt_for_linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscryptLinus Torvalds2019-05-071-0/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull fscrypt updates from Ted Ts'o: "Clean up fscrypt's dcache revalidation support, and other miscellaneous cleanups" * tag 'fscrypt_for_linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt: fscrypt: cache decrypted symlink target in ->i_link vfs: use READ_ONCE() to access ->i_link fscrypt: fix race where ->lookup() marks plaintext dentry as ciphertext fscrypt: only set dentry_operations on ciphertext dentries fs, fscrypt: clear DCACHE_ENCRYPTED_NAME when unaliasing directory fscrypt: fix race allowing rename() and link() of ciphertext dentries fscrypt: clean up and improve dentry revalidation fscrypt: use READ_ONCE() to access ->i_crypt_info fscrypt: remove WARN_ON_ONCE() when decryption fails fscrypt: drop inode argument from fscrypt_get_ctx()
| * fs, fscrypt: clear DCACHE_ENCRYPTED_NAME when unaliasing directoryEric Biggers2019-04-171-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Make __d_move() clear DCACHE_ENCRYPTED_NAME on the source dentry. This is needed for when d_splice_alias() moves a directory's encrypted alias to its decrypted alias as a result of the encryption key being added. Otherwise, the decrypted alias will incorrectly be invalidated on the next lookup, causing problems such as unmounting a mount the user just mount()ed there. Note that we don't have to support arbitrary moves of this flag because fscrypt doesn't allow dentries with DCACHE_ENCRYPTED_NAME to be the source or target of a rename(). Fixes: 28b4c263961c ("ext4 crypto: revalidate dentry after adding or removing the key") Reported-by: Sarthak Kukreti <sarthakkukreti@chromium.org> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
* | ovl_lookup_real_one(): don't bother with strlen()Al Viro2019-04-261-8/+6
| | | | | | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | unexport d_alloc_pseudo()Al Viro2019-04-091-1/+3
| | | | | | | | | | | | | | | | No modular uses since introducion of alloc_file_pseudo(), and the only non-modular user not in alloc_file_pseudo() had actually been wrong - should've been d_alloc_anon(). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | dcache: sort the freeing-without-RCU-delay mess for good.Al Viro2019-04-091-11/+13
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For lockless accesses to dentries we don't have pinned we rely (among other things) upon having an RCU delay between dropping the last reference and actually freeing the memory. On the other hand, for things like pipes and sockets we neither do that kind of lockless access, nor want to deal with the overhead of an RCU delay every time a socket gets closed. So delay was made optional - setting DCACHE_RCUACCESS in ->d_flags made sure it would happen. We tried to avoid setting it unless we knew we need it. Unfortunately, that had led to recurring class of bugs, in which we missed the need to set it. We only really need it for dentries that are created by d_alloc_pseudo(), so let's not bother with trying to be smart - just make having an RCU delay the default. The ones that do *not* get it set the replacement flag (DCACHE_NORCU) and we'd better use that sparingly. d_alloc_pseudo() is the only such user right now. FWIW, the race that finally prompted that switch had been between __lock_parent() of immediate subdirectory of what's currently the root of a disconnected tree (e.g. from open-by-handle in progress) racing with d_splice_alias() elsewhere picking another alias for the same inode, either on outright corrupted fs image, or (in case of open-by-handle on NFS) that subdirectory having been just moved on server. It's not easy to hit, so the sky is not falling, but that's not the first race on similar missed cases and the logics for settinf DCACHE_RCUACCESS has gotten ridiculously convoluted. Cc: stable@vger.kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* fs/dcache: Track & report number of negative dentriesWaiman Long2019-01-301-0/+32
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The current dentry number tracking code doesn't distinguish between positive & negative dentries. It just reports the total number of dentries in the LRU lists. As excessive number of negative dentries can have an impact on system performance, it will be wise to track the number of positive and negative dentries separately. This patch adds tracking for the total number of negative dentries in the system LRU lists and reports it in the 5th field in the /proc/sys/fs/dentry-state file. The number, however, does not include negative dentries that are in flight but not in the LRU yet as well as those in the shrinker lists which are on the way out anyway. The number of positive dentries in the LRU lists can be roughly found by subtracting the number of negative dentries from the unused count. Matthew Wilcox had confirmed that since the introduction of the dentry_stat structure in 2.1.60, the dummy array was there, probably for future extension. They were not replacements of pre-existing fields. So no sane applications that read the value of /proc/sys/fs/dentry-state will do dummy thing if the last 2 fields of the sysctl parameter are not zero. IOW, it will be safe to use one of the dummy array entry for negative dentry count. Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fs/dcache: Fix incorrect nr_dentry_unused accounting in shrink_dcache_sb()Waiman Long2019-01-301-5/+1
| | | | | | | | | | | | | | | | | | | The nr_dentry_unused per-cpu counter tracks dentries in both the LRU lists and the shrink lists where the DCACHE_LRU_LIST bit is set. The shrink_dcache_sb() function moves dentries from the LRU list to a shrink list and subtracts the dentry count from nr_dentry_unused. This is incorrect as the nr_dentry_unused count will also be decremented in shrink_dentry_list() via d_shrink_del(). To fix this double decrement, the decrement in the shrink_dcache_sb() function is taken out. Fixes: 4e717f5c1083 ("list_lru: remove special case function list_lru_dispose_all." Cc: stable@kernel.org Signed-off-by: Waiman Long <longman@redhat.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: remove include/linux/bootmem.hMike Rapoport2018-10-311-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Move remaining definitions and declarations from include/linux/bootmem.h into include/linux/memblock.h and remove the redundant header. The includes were replaced with the semantic patch below and then semi-automated removal of duplicated '#include <linux/memblock.h> @@ @@ - #include <linux/bootmem.h> + #include <linux/memblock.h> [sfr@canb.auug.org.au: dma-direct: fix up for the removal of linux/bootmem.h] Link: http://lkml.kernel.org/r/20181002185342.133d1680@canb.auug.org.au [sfr@canb.auug.org.au: powerpc: fix up for removal of linux/bootmem.h] Link: http://lkml.kernel.org/r/20181005161406.73ef8727@canb.auug.org.au [sfr@canb.auug.org.au: x86/kaslr, ACPI/NUMA: fix for linux/bootmem.h removal] Link: http://lkml.kernel.org/r/20181008190341.5e396491@canb.auug.org.au Link: http://lkml.kernel.org/r/1536927045-23536-30-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chris Zankel <chris@zankel.net> Cc: "David S. Miller" <davem@davemloft.net> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greentime Hu <green.hu@gmail.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Ingo Molnar <mingo@redhat.com> Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Jonas Bonn <jonas@southpole.se> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Ley Foon Tan <lftan@altera.com> Cc: Mark Salter <msalter@redhat.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Palmer Dabbelt <palmer@sifive.com> Cc: Paul Burton <paul.burton@mips.com> Cc: Richard Kuo <rkuo@codeaurora.org> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Serge Semin <fancer.lancer@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* dcache: allocate external names from reclaimable kmalloc cachesVlastimil Babka2018-10-261-29/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | We can use the newly introduced kmalloc-reclaimable-X caches, to allocate external names in dcache, which will take care of the proper accounting automatically, and also improve anti-fragmentation page grouping. This effectively reverts commit f1782c9bc547 ("dcache: account external names as indirectly reclaimable memory") and instead passes __GFP_RECLAIMABLE to kmalloc(). The accounting thus moves from NR_INDIRECTLY_RECLAIMABLE_BYTES to NR_SLAB_RECLAIMABLE, which is also considered in MemAvailable calculation and overcommit decisions. Link: http://lkml.kernel.org/r/20180731090649.16028-4-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Roman Gushchin <guro@fb.com> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Laura Abbott <labbott@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: Vijayanand Jitta <vjitta@codeaurora.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fs/dcache.c: fix kmemcheck splat at take_dentry_name_snapshot()Tetsuo Handa2018-08-171-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since only dentry->d_name.len + 1 bytes out of DNAME_INLINE_LEN bytes are initialized at __d_alloc(), we can't copy the whole size unconditionally. WARNING: kmemcheck: Caught 32-bit read from uninitialized memory (ffff8fa27465ac50) 636f6e66696766732e746d70000000000010000000000000020000000188ffff i i i i i i i i i i i i i u u u u u u u u u u i i i i i u u u u ^ RIP: 0010:take_dentry_name_snapshot+0x28/0x50 RSP: 0018:ffffa83000f5bdf8 EFLAGS: 00010246 RAX: 0000000000000020 RBX: ffff8fa274b20550 RCX: 0000000000000002 RDX: ffffa83000f5be40 RSI: ffff8fa27465ac50 RDI: ffffa83000f5be60 RBP: ffffa83000f5bdf8 R08: ffffa83000f5be48 R09: 0000000000000001 R10: ffff8fa27465ac00 R11: ffff8fa27465acc0 R12: ffff8fa27465ac00 R13: ffff8fa27465acc0 R14: 0000000000000000 R15: 0000000000000000 FS: 00007f79737ac8c0(0000) GS:ffffffff8fc30000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff8fa274c0b000 CR3: 0000000134aa7002 CR4: 00000000000606f0 take_dentry_name_snapshot+0x28/0x50 vfs_rename+0x128/0x870 SyS_rename+0x3b2/0x3d0 entry_SYSCALL_64_fastpath+0x1a/0xa4 0xffffffffffffffff Link: http://lkml.kernel.org/r/201709131912.GBG39012.QMJLOVFSFFOOtH@I-love.SAKURA.ne.jp Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Vegard Nossum <vegard.nossum@gmail.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>
*-. Merge branches 'work.misc' and 'work.dcache' of ↵Linus Torvalds2018-08-131-33/+6
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull misc vfs updates from Al Viro: "Misc cleanups from various folks all over the place I expected more fs/dcache.c cleanups this cycle, so that went into a separate branch. Said cleanups have missed the window, so in the hindsight it could've gone into work.misc instead. Decided not to cherry-pick, thus the 'work.dcache' branch" * 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: fs: dcache: Use true and false for boolean values fold generic_readlink() into its only caller fs: shave 8 bytes off of struct inode fs: Add more kernel-doc to the produced documentation fs: Fix attr.c kernel-doc removed extra extern file_fdatawait_range * 'work.dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: kill dentry_update_name_case()
| | * kill dentry_update_name_case()Al Viro2018-06-231-27/+0
| | | | | | | | | | | | | | | | | | | | | the last user is gone Spotted-by: Richard Weinberger <richard@nod.at> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| * | fs: dcache: Use true and false for boolean valuesGustavo A. R. Silva2018-08-051-6/+6
| |/ | | | | | | | | | | | | | | | | | | Return statements in functions returning bool should use true or false instead of an integer value. This issue was detected with the help of Coccinelle. Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | Merge branch 'work.mkdir' of ↵Linus Torvalds2018-08-131-28/+1
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs icache updates from Al Viro: - NFS mkdir/open_by_handle race fix - analogous solution for FUSE, replacing the one currently in mainline - new primitive to be used when discarding halfway set up inodes on failed object creation; gives sane warranties re icache lookups not returning such doomed by still not freed inodes. A bunch of filesystems switched to that animal. - Miklos' fix for last cycle regression in iget5_locked(); -stable will need a slightly different variant, unfortunately. - misc bits and pieces around things icache-related (in adfs and jfs). * 'work.mkdir' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: jfs: don't bother with make_bad_inode() in ialloc() adfs: don't put inodes into icache new helper: inode_fake_hash() vfs: don't evict uninitialized inode jfs: switch to discard_new_inode() ext2: make sure that partially set up inodes won't be returned by ext2_iget() udf: switch to discard_new_inode() ufs: switch to discard_new_inode() btrfs: switch to discard_new_inode() new primitive: discard_new_inode() kill d_instantiate_no_diralias() nfs_instantiate(): prevent multiple aliases for directory inode
| * | new primitive: discard_new_inode()Al Viro2018-08-031-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We don't want open-by-handle picking half-set-up in-core struct inode from e.g. mkdir() having failed halfway through. In other words, we don't want such inodes returned by iget_locked() on their way to extinction. However, we can't just have them unhashed - otherwise open-by-handle immediately *after* that would've ended up creating a new in-core inode over the on-disk one that is in process of being freed right under us. Solution: new flag (I_CREATING) set by insert_inode_locked() and removed by unlock_new_inode() and a new primitive (discard_new_inode()) to be used by such halfway-through-setup failure exits instead of unlock_new_inode() / iput() combinations. That primitive unlocks new inode, but leaves I_CREATING in place. iget_locked() treats finding an I_CREATING inode as failure (-ESTALE, once we sort out the error propagation). insert_inode_locked() treats the same as instant -EBUSY. ilookup() treats those as icache miss. [Fix by Dan Carpenter <dan.carpenter@oracle.com> folded in] Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| * | kill d_instantiate_no_diralias()Al Viro2018-08-011-27/+0
| |/ | | | | | | | | | | | | | | | | | | | | | | | | The only user is fuse_create_new_entry(), and there it's used to mitigate the same mkdir/open-by-handle race as in nfs_mkdir(). The same solution applies - unhash the mkdir argument, then call d_splice_alias() and if that returns a reference to preexisting alias, dput() and report success. ->mkdir() argument left unhashed negative with the preexisting alias moved in the right place is just fine from the ->mkdir() callers point of view. Cc: Miklos Szeredi <miklos@szeredi.hu> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | make sure that __dentry_kill() always invalidates d_seq, unhashed or notAl Viro2018-08-091-5/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | RCU pathwalk relies upon the assumption that anything that changes ->d_inode of a dentry will invalidate its ->d_seq. That's almost true - the one exception is that the final dput() of already unhashed dentry does *not* touch ->d_seq at all. Unhashing does, though, so for anything we'd found by RCU dcache lookup we are fine. Unfortunately, we can *start* with an unhashed dentry or jump into it. We could try and be careful in the (few) places where that could happen. Or we could just make the final dput() invalidate the damn thing, unhashed or not. The latter is much simpler and easier to backport, so let's do it that way. Reported-by: "Dae R. Jeong" <threeearcat@gmail.com> Cc: stable@vger.kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | root dentries need RCU-delayed freeingAl Viro2018-08-061-2/+4
|/ | | | | | | | | | | | | | | | | | Since mountpoint crossing can happen without leaving lazy mode, root dentries do need the same protection against having their memory freed without RCU delay as everything else in the tree. It's partially hidden by RCU delay between detaching from the mount tree and dropping the vfsmount reference, but the starting point of pathwalk can be on an already detached mount, in which case umount-caused RCU delay has already passed by the time the lazy pathwalk grabs rcu_read_lock(). If the starting point happens to be at the root of that vfsmount *and* that vfsmount covers the entire filesystem, we get trouble. Fixes: 48a066e72d97 ("RCU'd vsfmounts") Cc: stable@vger.kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* Merge branch 'work.misc' of ↵Linus Torvalds2018-06-041-49/+34
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull misc vfs updates from Al Viro: "Misc bits and pieces not fitting into anything more specific" * 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: vfs: delete unnecessary assignment in vfs_listxattr Documentation: filesystems: update filesystem locking documentation vfs: namei: use path_equal() in follow_dotdot() fs.h: fix outdated comment about file flags __inode_security_revalidate() never gets NULL opt_dentry make xattr_getsecurity() static vfat: simplify checks in vfat_lookup() get rid of dead code in d_find_alias() it's SB_BORN, not MS_BORN... msdos_rmdir(): kill BS comment remove rpc_rmdir() fs: avoid fdput() after failed fdget() in vfs_dedupe_file_range()
| * get rid of dead code in d_find_alias()Al Viro2018-05-131-49/+34
| | | | | | | | | | | | | | | | | | | | All "try disconnected alias if nothing else fits" logics in d_find_alias() got accidentally disabled by Neil a while ago; for most of the callers it was the right thing to do, so fixes belong in few callers that *do* want disconnected aliases. This just takes the now-dead code in d_find_alias() out. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | Merge branch 'work.dcache' of ↵Linus Torvalds2018-06-041-79/+43
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull dcache updates from Al Viro: "This is the first part of dealing with livelocks etc around shrink_dcache_parent()." * 'work.dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: restore cond_resched() in shrink_dcache_parent() dput(): turn into explicit while() loop dcache: move cond_resched() into the end of __dentry_kill() d_walk(): kill 'finish' callback d_invalidate(): unhash immediately
| * | restore cond_resched() in shrink_dcache_parent()Al Viro2018-04-191-2/+7
| | | | | | | | | | | | Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| * | dput(): turn into explicit while() loopAl Viro2018-04-151-18/+13
| | | | | | | | | | | | | | | | | | | | | No need to mess with gotos when the code yielded by straight while() isn't any worse... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| * | dcache: move cond_resched() into the end of __dentry_kill()Al Viro2018-04-151-3/+1
| | | | | | | | | | | | | | | | | | cond_resched() in shrink_dentry_list() is too early Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| * | d_walk(): kill 'finish' callbackAl Viro2018-04-151-11/+7
| | | | | | | | | | | | | | | | | | no users left Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| * | d_invalidate(): unhash immediatelyAl Viro2018-04-151-46/+16
| |/ | | | | | | | | | | | | | | Once that is done, we can just hunt mountpoints down one by one; no new mountpoints can be added from now on, so we don't need anything tricky in finish() callback, etc. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* / do d_instantiate/unlock_new_inode combinations safelyAl Viro2018-05-111-0/+22
|/ | | | | | | | | | | | | | | | | | | | | | | | | For anything NFS-exported we do _not_ want to unlock new inode before it has grown an alias; original set of fixes got the ordering right, but missed the nasty complication in case of lockdep being enabled - unlock_new_inode() does lockdep_annotate_inode_mutex_key(inode) which can only be done before anyone gets a chance to touch ->i_mutex. Unfortunately, flipping the order and doing unlock_new_inode() before d_instantiate() opens a window when mkdir can race with open-by-fhandle on a guessed fhandle, leading to multiple aliases for a directory inode and all the breakage that follows from that. Correct solution: a new primitive (d_instantiate_new()) combining these two in the right order - lockdep annotate, then d_instantiate(), then the rest of unlock_new_inode(). All combinations of d_instantiate() with unlock_new_inode() should be converted to that. Cc: stable@kernel.org # 2.6.29 and later Tested-by: Mike Marshall <hubcap@omnibond.com> Reviewed-by: Andreas Dilger <adilger@dilger.ca> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* fs/dcache.c: add cond_resched() in shrink_dentry_list()Nikolay Borisov2018-04-111-3/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | As previously reported (https://patchwork.kernel.org/patch/8642031/) it's possible to call shrink_dentry_list with a large number of dentries (> 10000). This, in turn, could trigger the softlockup detector and possibly trigger a panic. In addition to the unmount path being vulnerable to this scenario, at SuSE we've observed similar situation happening during process exit on processes that touch a lot of dentries. Here is an excerpt from a crash dump. The number after the colon are the number of dentries on the list passed to shrink_dentry_list: PID 99760: 10722 PID 107530: 215 PID 108809: 24134 PID 108877: 21331 PID 141708: 16487 So we want to kill between 15k-25k dentries without yielding. And one possible call stack looks like: 4 [ffff8839ece41db0] _raw_spin_lock at ffffffff8152a5f8 5 [ffff8839ece41db0] evict at ffffffff811c3026 6 [ffff8839ece41dd0] __dentry_kill at ffffffff811bf258 7 [ffff8839ece41df0] shrink_dentry_list at ffffffff811bf593 8 [ffff8839ece41e18] shrink_dcache_parent at ffffffff811bf830 9 [ffff8839ece41e50] proc_flush_task at ffffffff8120dd61 10 [ffff8839ece41ec0] release_task at ffffffff81059ebd 11 [ffff8839ece41f08] do_exit at ffffffff8105b8ce 12 [ffff8839ece41f78] sys_exit at ffffffff8105bd53 13 [ffff8839ece41f80] system_call_fastpath at ffffffff81532909 While some of the callers of shrink_dentry_list do use cond_resched, this is not sufficient to prevent softlockups. So just move cond_resched into shrink_dentry_list from its callers. David said: I've found hundreds of occurrences of warnings that we emit when need_resched stays set for a prolonged period of time with the stack trace that is included in the change log. Link: http://lkml.kernel.org/r/1521718946-31521-1-git-send-email-nborisov@suse.com Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: David Rientjes <rientjes@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Goldwyn Rodrigues <rgoldwyn@suse.de> Cc: Jeff Mahoney <jeffm@suse.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* dcache: account external names as indirectly reclaimable memoryRoman Gushchin2018-04-111-9/+30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | I received a report about suspicious growth of unreclaimable slabs on some machines. I've found that it happens on machines with low memory pressure, and these unreclaimable slabs are external names attached to dentries. External names are allocated using generic kmalloc() function, so they are accounted as unreclaimable. But they are held by dentries, which are reclaimable, and they will be reclaimed under the memory pressure. In particular, this breaks MemAvailable calculation, as it doesn't take unreclaimable slabs into account. This leads to a silly situation, when a machine is almost idle, has no memory pressure and therefore has a big dentry cache. And the resulting MemAvailable is too low to start a new workload. To address the issue, the NR_INDIRECTLY_RECLAIMABLE_BYTES counter is used to track the amount of memory, consumed by external names. The counter is increased in the dentry allocation path, if an external name structure is allocated; and it's decreased in the dentry freeing path. To reproduce the problem I've used the following Python script: import os for iter in range (0, 10000000): try: name = ("/some_long_name_%d" % iter) + "_" * 220 os.stat(name) except Exception: pass Without this patch: $ cat /proc/meminfo | grep MemAvailable MemAvailable: 7811688 kB $ python indirect.py $ cat /proc/meminfo | grep MemAvailable MemAvailable: 2753052 kB With the patch: $ cat /proc/meminfo | grep MemAvailable MemAvailable: 7809516 kB $ python indirect.py $ cat /proc/meminfo | grep MemAvailable MemAvailable: 7749144 kB [guro@fb.com: fix indirectly reclaimable memory accounting for CONFIG_SLOB] Link: http://lkml.kernel.org/r/20180312194140.19517-1-guro@fb.com [guro@fb.com: fix indirectly reclaimable memory accounting] Link: http://lkml.kernel.org/r/20180313125701.7955-1-guro@fb.com Link: http://lkml.kernel.org/r/20180305133743.12746-5-guro@fb.com Signed-off-by: Roman Gushchin <guro@fb.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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