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2022-04-09fscache: Move fscache_cookies_seq_ops specific code under CONFIG_PROC_FSYue Hu1-1/+3
fscache_cookies_seq_ops is only used in proc.c that is compiled under enabled CONFIG_PROC_FS, so move related code under this config. The same case exsits in internal.h. Also, make fscache_lru_cookie_timeout static due to no user outside of cookie.c. Signed-off-by: Yue Hu <huyue2@coolpad.com> Signed-off-by: David Howells <dhowells@redhat.com> cc: linux-cachefs@redhat.com Link: https://listman.redhat.com/archives/linux-cachefs/2022-April/006649.html # v1
2022-01-12fscache: Add a tracepoint for cookie use/unuseDavid Howells1-4/+25
Add a tracepoint to track fscache_use/unuse_cookie(). Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/164021588628.640689.12942919367404043608.stgit@warthog.procyon.org.uk/ # v4
2022-01-07fscache: Implement cookie invalidationDavid Howells1-1/+87
Add a function to invalidate the cache behind a cookie: void fscache_invalidate(struct fscache_cookie *cookie, const void *aux_data, loff_t size, unsigned int flags) This causes any cached data for the specified cookie to be discarded. If the cookie is marked as being in use, a new cache object will be created if possible and future I/O will use that instead. In-flight I/O should be abandoned (writes) or reconsidered (reads). Each time it is called cookie->inval_counter is incremented and this can be used to detect invalidation at the end of an I/O operation. The coherency data attached to the cookie can be updated and the cookie size should be reset. One flag is available, FSCACHE_INVAL_DIO_WRITE, which should be used to indicate invalidation due to a DIO write on a file. This will temporarily disable caching for this cookie. Changes ======= ver #2: - Should only change to inval state if can get access to cache. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/163819602231.215744.11206598147269491575.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906909707.143852.18056070560477964891.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/163967107447.1823006.5945029409592119962.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/164021512640.640689.11418616313147754172.stgit@warthog.procyon.org.uk/ # v4
2022-01-07fscache: Implement cookie user counting and resource pinningDavid Howells1-1/+217
Provide a pair of functions to count the number of users of a cookie (open files, writeback, invalidation, resizing, reads, writes), to obtain and pin resources for the cookie and to prevent culling for the whilst there are users. The first function marks a cookie as being in use: void fscache_use_cookie(struct fscache_cookie *cookie, bool will_modify); The caller should indicate the cookie to use and whether or not the caller is in a context that may modify the cookie (e.g. a file open O_RDWR). If the cookie is not already resourced, fscache will ask the cache backend in the background to do whatever it needs to look up, create or otherwise obtain the resources necessary to access data. This is pinned to the cookie and may not be culled, though it may be withdrawn if the cache as a whole is withdrawn. The second function removes the in-use mark from a cookie and, optionally, updates the coherency data: void fscache_unuse_cookie(struct fscache_cookie *cookie, const void *aux_data, const loff_t *object_size); If non-NULL, the aux_data buffer and/or the object_size will be saved into the cookie and will be set on the backing store when the object is committed. If this removes the last usage on a cookie, the cookie is placed onto an LRU list from which it will be removed and closed after a couple of seconds if it doesn't get reused. This prevents resource overload in the cache - in particular it prevents it from holding too many files open. Changes ======= ver #2: - Fix fscache_unuse_cookie() to use atomic_dec_and_lock() to avoid a potential race if the cookie gets reused before it completes the unusement. - Added missing transition to LRU_DISCARDING state. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/163819600612.215744.13678350304176542741.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906907567.143852.16979631199380722019.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/163967106467.1823006.6790864931048582667.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/164021511674.640689.10084988363699111860.stgit@warthog.procyon.org.uk/ # v4
2022-01-07fscache: Implement simple cookie state machineDavid Howells1-42/+271
Implement a very simple cookie state machine to handle lookup, invalidation, withdrawal, relinquishment and, to be added later, commit on LRU discard. Three cache methods are provided: ->lookup_cookie() to look up and, if necessary, create a data storage object; ->withdraw_cookie() to free the resources associated with that object and potentially delete it; and ->prepare_to_write(), to do prepare for changes to the cached data to be modified locally. Changes ======= ver #3: - Fix a race between LRU discard and relinquishment whereby the former would override the latter and thus the latter would never happen[1]. ver #2: - Don't hold n_accesses elevated whilst cache is bound to a cookie, but rather add a flag that prevents the state machine from being queued when n_accesses reaches 0. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/599331.1639410068@warthog.procyon.org.uk/ [1] Link: https://lore.kernel.org/r/163819599657.215744.15799615296912341745.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906903925.143852.1805855338154353867.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/163967105456.1823006.14730395299835841776.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/164021510706.640689.7961423370243272583.stgit@warthog.procyon.org.uk/ # v4
2022-01-07fscache: Implement cookie-level access helpersDavid Howells1-0/+98
Add a number of helper functions to manage access to a cookie, pinning the cache object in place for the duration to prevent cache withdrawal from removing it: (1) void fscache_init_access_gate(struct fscache_cookie *cookie); This function initialises the access count when a cache binds to a cookie. An extra ref is taken on the access count to prevent wakeups while the cache is active. We're only interested in the wakeup when a cookie is being withdrawn and we're waiting for it to quiesce - at which point the counter will be decremented before the wait. The FSCACHE_COOKIE_NACC_ELEVATED flag is set on the cookie to keep track of the extra ref in order to handle a race between relinquishment and withdrawal both trying to drop the extra ref. (2) bool fscache_begin_cookie_access(struct fscache_cookie *cookie, enum fscache_access_trace why); This function attempts to begin access upon a cookie, pinning it in place if it's cached. If successful, it returns true and leaves a the access count incremented. (3) void fscache_end_cookie_access(struct fscache_cookie *cookie, enum fscache_access_trace why); This function drops the access count obtained by (2), permitting object withdrawal to take place when it reaches zero. A tracepoint is provided to track changes to the access counter on a cookie. Changes ======= ver #2: - Don't hold n_accesses elevated whilst cache is bound to a cookie, but rather add a flag that prevents the state machine from being queued when n_accesses reaches 0. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/163819595085.215744.1706073049250505427.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906895313.143852.10141619544149102193.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/163967095980.1823006.1133648159424418877.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/164021503063.640689.8870918985269528670.stgit@warthog.procyon.org.uk/ # v4
2022-01-07fscache: Implement cookie registrationDavid Howells1-0/+497
Add functions to the fscache API to allow data file cookies to be acquired and relinquished by the network filesystem. It is intended that the filesystem will create such cookies per-inode under a volume. To request a cookie, the filesystem should call: struct fscache_cookie * fscache_acquire_cookie(struct fscache_volume *volume, u8 advice, const void *index_key, size_t index_key_len, const void *aux_data, size_t aux_data_len, loff_t object_size) The filesystem must first have created a volume cookie, which is passed in here. If it passes in NULL then the function will just return a NULL cookie. A binary key should be passed in index_key and is of size index_key_len. This is saved in the cookie and is used to locate the associated data in the cache. A coherency data buffer of size aux_data_len will be allocated and initialised from the buffer pointed to by aux_data. This is used to validate cache objects when they're opened and is stored on disk with them when they're committed. The data is stored in the cookie and will be updateable by various functions in later patches. The object_size must also be given. This is also used to perform a coherency check and to size the backing storage appropriately. This function disallows a cookie from being acquired twice in parallel, though it will cause the second user to wait if the first is busy relinquishing its cookie. When a network filesystem has finished with a cookie, it should call: void fscache_relinquish_cookie(struct fscache_volume *volume, bool retire) If retire is true, any backing data will be discarded immediately. Changes ======= ver #3: - fscache_hash()'s size parameter is now in bytes. Use __le32 as the unit to round up to. - When comparing cookies, simply see if the attributes are the same rather than subtracting them to produce a strcmp-style return[1]. - Add a check to see if the cookie is still hashed at the point of freeing. ver #2: - Don't hold n_accesses elevated whilst cache is bound to a cookie, but rather add a flag that prevents the state machine from being queued when n_accesses reaches 0. - Remove the unused cookie pointer field from the fscache_acquire tracepoint. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/CAHk-=whtkzB446+hX0zdLsdcUJsJ=8_-0S1mE_R+YurThfUbLA@mail.gmail.com/ [1] Link: https://lore.kernel.org/r/163819590658.215744.14934902514281054323.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906891983.143852.6219772337558577395.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/163967088507.1823006.12659006350221417165.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/164021498432.640689.12743483856927722772.stgit@warthog.procyon.org.uk/ # v4
2022-01-07fscache: Remove the contents of the fscache driver, pending rewriteDavid Howells1-1071/+0
Remove the code that comprises the fscache driver as it's going to be substantially rewritten, with the majority of the code being erased in the rewrite. A small piece of linux/fscache.h is left as that is #included by a bunch of network filesystems. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/163819578724.215744.18210619052245724238.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906884814.143852.6727245089843862889.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/163967077097.1823006.1377665951499979089.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/164021485548.640689.13876080567388696162.stgit@warthog.procyon.org.uk/ # v4
2021-08-27fscache: Use refcount_t for the cookie refcount instead of atomic_tDavid Howells1-10/+21
Use refcount_t for the fscache_cookie refcount instead of atomic_t and rename the 'usage' member to 'ref' in such cases. The tracepoints that reference it change from showing "u=%d" to "r=%d". Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@redhat.com> cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/162431204358.2908479.8006938388213098079.stgit@warthog.procyon.org.uk/
2021-08-27fscache: Fix fscache_cookie_put() to not deref after decDavid Howells1-4/+6
fscache_cookie_put() accesses the cookie it has just put inside the tracepoint that monitors the change - but this is something it's not allowed to do if we didn't reduce the count to zero. Fix this by dropping most of those values from the tracepoint and grabbing the cookie debug ID before doing the dec. Also take the opportunity to switch over the usage and where arguments on the tracepoint to put the reason last. Fixes: a18feb55769b ("fscache: Add tracepoints") Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@redhat.com> cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/162431203107.2908479.3259582550347000088.stgit@warthog.procyon.org.uk/
2021-08-27fscache: Fix cookie key hashingDavid Howells1-13/+1
The current hash algorithm used for hashing cookie keys is really bad, producing almost no dispersion (after a test kernel build, ~30000 files were split over just 18 out of the 32768 hash buckets). Borrow the full_name_hash() hash function into fscache to do the hashing for cookie keys and, in the future, volume keys. I don't want to use full_name_hash() as-is because I want the hash value to be consistent across arches and over time as the hash value produced may get used on disk. I can also optimise parts of it away as the key will always be a padded array of aligned 32-bit words. Fixes: ec0328e46d6e ("fscache: Maintain a catalogue of allocated cookies") Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@redhat.com> cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/162431201844.2908479.8293647220901514696.stgit@warthog.procyon.org.uk/
2021-08-27fscache: Change %p in format strings to something elseDavid Howells1-9/+7
Change plain %p in format strings in fscache code to something more useful, since %p is now hashed before printing and thus no longer matches the contents of an oops register dump. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@redhat.com> cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/160588474843.3465195.5446072310069374803.stgit@warthog.procyon.org.uk/ # rfc Link: https://lore.kernel.org/r/162431199509.2908479.2950631488219944294.stgit@warthog.procyon.org.uk/
2021-08-27fscache: Remove the object list procfileDavid Howells1-2/+0
Remove the object list procfile from fscache as objects will become entirely internal to the cache. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@redhat.com> cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/162431198332.2908479.5847286163455099669.stgit@warthog.procyon.org.uk/
2021-08-27fscache: Procfile to display cookiesDavid Howells1-0/+103
Add /proc/fs/fscache/cookies to display active cookies. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@redhat.com> cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/158861211871.340223.7223853943667440807.stgit@warthog.procyon.org.uk/ # rfc Link: https://lore.kernel.org/r/159465771021.1376105.6933857529128238020.stgit@warthog.procyon.org.uk/ Link: https://lore.kernel.org/r/160588460994.3465195.16963417803501149328.stgit@warthog.procyon.org.uk/ # rfc Link: https://lore.kernel.org/r/162431194785.2908479.786917990782538164.stgit@warthog.procyon.org.uk/
2021-08-27fscache: Add a cookie debug ID and use that in tracesDavid Howells1-9/+20
Add a cookie debug ID and use that in traces and in procfiles rather than displaying the (hashed) pointer to the cookie. This is easier to correlate and we don't lose anything when interpreting oops output since that shows unhashed addresses and registers that aren't comparable to the hashed values. Changes: ver #2: - Fix the fscache_op tracepoint to handle a NULL cookie pointer. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@redhat.com> cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/158861210988.340223.11688464116498247790.stgit@warthog.procyon.org.uk/ # rfc Link: https://lore.kernel.org/r/159465769844.1376105.14119502774019865432.stgit@warthog.procyon.org.uk/ Link: https://lore.kernel.org/r/160588459097.3465195.1273313637721852165.stgit@warthog.procyon.org.uk/ # rfc Link: https://lore.kernel.org/r/162431193544.2908479.17556704572948300790.stgit@warthog.procyon.org.uk/
2020-05-05docs: filesystems: caching/netfs-api.txt: convert it to ReSTMauro Carvalho Chehab1-1/+1
- Add a SPDX header; - Adjust document and section titles; - Some whitespace fixes and new line breaks; - Mark literal blocks as such; - Add it to filesystems/caching/index.rst. Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Link: https://lore.kernel.org/r/cfe4cb1bf8e1f0093d44c30801ec42e74721e543.1588021877.git.mchehab+huawei@kernel.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-05-30treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152Thomas Gleixner1-5/+1
Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 3029 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-10-18fscache: Fix out of bound read in long cookie keysEric Sandeen1-3/+7
fscache_set_key() can incur an out-of-bounds read, reported by KASAN: BUG: KASAN: slab-out-of-bounds in fscache_alloc_cookie+0x5b3/0x680 [fscache] Read of size 4 at addr ffff88084ff056d4 by task mount.nfs/32615 and also reported by syzbot at https://lkml.org/lkml/2018/7/8/236 BUG: KASAN: slab-out-of-bounds in fscache_set_key fs/fscache/cookie.c:120 [inline] BUG: KASAN: slab-out-of-bounds in fscache_alloc_cookie+0x7a9/0x880 fs/fscache/cookie.c:171 Read of size 4 at addr ffff8801d3cc8bb4 by task syz-executor907/4466 This happens for any index_key_len which is not divisible by 4 and is larger than the size of the inline key, because the code allocates exactly index_key_len for the key buffer, but the hashing loop is stepping through it 4 bytes (u32) at a time in the buf[] array. Fix this by calculating how many u32 buffers we'll need by using DIV_ROUND_UP, and then using kcalloc() to allocate a precleared allocation buffer to hold the index_key, then using that same count as the hashing index limit. Fixes: ec0328e46d6e ("fscache: Maintain a catalogue of allocated cookies") Reported-by: syzbot+a95b989b2dde8e806af8@syzkaller.appspotmail.com Signed-off-by: Eric Sandeen <sandeen@redhat.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-10-18fscache: Fix incomplete initialisation of inline key spaceDavid Howells1-19/+4
The inline key in struct rxrpc_cookie is insufficiently initialized, zeroing only 3 of the 4 slots, therefore an index_key_len between 13 and 15 bytes will end up hashing uninitialized memory because the memcpy only partially fills the last buf[] element. Fix this by clearing fscache_cookie objects on allocation rather than using the slab constructor to initialise them. We're going to pretty much fill in the entire struct anyway, so bringing it into our dcache writably shouldn't incur much overhead. This removes the need to do clearance in fscache_set_key() (where we aren't doing it correctly anyway). Also, we don't need to set cookie->key_len in fscache_set_key() as we already did it in the only caller, so remove that. Fixes: ec0328e46d6e ("fscache: Maintain a catalogue of allocated cookies") Reported-by: syzbot+a95b989b2dde8e806af8@syzkaller.appspotmail.com Reported-by: Eric Sandeen <sandeen@redhat.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-07-25fscache: Fix reference overput in fscache_attach_object() error handlingKiran Kumar Modukuri1-3/+4
When a cookie is allocated that causes fscache_object structs to be allocated, those objects are initialised with the cookie pointer, but aren't blessed with a ref on that cookie unless the attachment is successfully completed in fscache_attach_object(). If attachment fails because the parent object was dying or there was a collision, fscache_attach_object() returns without incrementing the cookie counter - but upon failure of this function, the object is released which then puts the cookie, whether or not a ref was taken on the cookie. Fix this by taking a ref on the cookie when it is assigned in fscache_object_init(), even when we're creating a root object. Analysis from Kiran Kumar: This bug has been seen in 4.4.0-124-generic #148-Ubuntu kernel BugLink: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1776277 fscache cookie ref count updated incorrectly during fscache object allocation resulting in following Oops. kernel BUG at /build/linux-Y09MKI/linux-4.4.0/fs/fscache/internal.h:321! kernel BUG at /build/linux-Y09MKI/linux-4.4.0/fs/fscache/cookie.c:639! [Cause] Two threads are trying to do operate on a cookie and two objects. (1) One thread tries to unmount the filesystem and in process goes over a huge list of objects marking them dead and deleting the objects. cookie->usage is also decremented in following path: nfs_fscache_release_super_cookie -> __fscache_relinquish_cookie ->__fscache_cookie_put ->BUG_ON(atomic_read(&cookie->usage) <= 0); (2) A second thread tries to lookup an object for reading data in following path: fscache_alloc_object 1) cachefiles_alloc_object -> fscache_object_init -> assign cookie, but usage not bumped. 2) fscache_attach_object -> fails in cant_attach_object because the cookie's backing object or cookie's->parent object are going away 3) fscache_put_object -> cachefiles_put_object ->fscache_object_destroy ->fscache_cookie_put ->BUG_ON(atomic_read(&cookie->usage) <= 0); [NOTE from dhowells] It's unclear as to the circumstances in which (2) can take place, given that thread (1) is in nfs_kill_super(), however a conflicting NFS mount with slightly different parameters that creates a different superblock would do it. A backtrace from Kiran seems to show that this is a possibility: kernel BUG at/build/linux-Y09MKI/linux-4.4.0/fs/fscache/cookie.c:639! ... RIP: __fscache_cookie_put+0x3a/0x40 [fscache] Call Trace: __fscache_relinquish_cookie+0x87/0x120 [fscache] nfs_fscache_release_super_cookie+0x2d/0xb0 [nfs] nfs_kill_super+0x29/0x40 [nfs] deactivate_locked_super+0x48/0x80 deactivate_super+0x5c/0x60 cleanup_mnt+0x3f/0x90 __cleanup_mnt+0x12/0x20 task_work_run+0x86/0xb0 exit_to_usermode_loop+0xc2/0xd0 syscall_return_slowpath+0x4e/0x60 int_ret_from_sys_call+0x25/0x9f [Fix] Bump up the cookie usage in fscache_object_init, when it is first being assigned a cookie atomically such that the cookie is added and bumped up if its refcount is not zero. Remove the assignment in fscache_attach_object(). [Testcase] I have run ~100 hours of NFS stress tests and not seen this bug recur. [Regression Potential] - Limited to fscache/cachefiles. Fixes: ccc4fc3d11e9 ("FS-Cache: Implement the cookie management part of the netfs API") Signed-off-by: Kiran Kumar Modukuri <kiran.modukuri@gmail.com> Signed-off-by: David Howells <dhowells@redhat.com>
2018-04-11fscache: use appropriate radix tree accessorsMatthew Wilcox1-1/+1
Don't open-code accesses to data structure internals. Link: http://lkml.kernel.org/r/20180313132639.17387-7-willy@infradead.org Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> Reviewed-by: Jeff Layton <jlayton@redhat.com> Cc: Darrick J. Wong <darrick.wong@oracle.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-06fscache: Maintain a catalogue of allocated cookiesDavid Howells1-56/+238
Maintain a catalogue of allocated cookies so that cookie collisions can be handled properly. For the moment, this just involves printing a warning and returning a NULL cookie to the caller of fscache_acquire_cookie(), but in future it might make sense to wait for the old cookie to finish being cleaned up. This requires the cookie key to be stored attached to the cookie so that we still have the key available if the netfs relinquishes the cookie. This is done by an earlier patch. The catalogue also renders redundant fscache_netfs_list (used for checking for duplicates), so that can be removed. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Anna Schumaker <anna.schumaker@netapp.com> Tested-by: Steve Dickson <steved@redhat.com>
2018-04-06fscache: Pass object size in rather than calling back for itDavid Howells1-9/+9
Pass the object size in to fscache_acquire_cookie() and fscache_write_page() rather than the netfs providing a callback by which it can be received. This makes it easier to update the size of the object when a new page is written that extends the object. The current object size is also passed by fscache to the check_aux function, obviating the need to store it in the aux data. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Anna Schumaker <anna.schumaker@netapp.com> Tested-by: Steve Dickson <steved@redhat.com>
2018-04-04fscache: Attach the index key and aux data to the cookieDavid Howells1-19/+69
Attach copies of the index key and auxiliary data to the fscache cookie so that: (1) The callbacks to the netfs for this stuff can be eliminated. This can simplify things in the cache as the information is still available, even after the cache has relinquished the cookie. (2) Simplifies the locking requirements of accessing the information as we don't have to worry about the netfs object going away on us. (3) The cache can do lazy updating of the coherency information on disk. As long as the cache is flushed before reboot/poweroff, there's no need to update the coherency info on disk every time it changes. (4) Cookies can be hashed or put in a tree as the index key is easily available. This allows: (a) Checks for duplicate cookies can be made at the top fscache layer rather than down in the bowels of the cache backend. (b) Caching can be added to a netfs object that has a cookie if the cache is brought online after the netfs object is allocated. A certain amount of space is made in the cookie for inline copies of the data, but if it won't fit there, extra memory will be allocated for it. The downside of this is that live cache operation requires more memory. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Anna Schumaker <anna.schumaker@netapp.com> Tested-by: Steve Dickson <steved@redhat.com>
2018-04-04fscache: Add more tracepointsDavid Howells1-1/+2
Add more tracepoints to fscache, including: (*) fscache_page - Tracks netfs pages known to fscache. (*) fscache_check_page - Tracks the netfs querying whether a page is pending storage. (*) fscache_wake_cookie - Tracks cookies being woken up after a page completes/aborts storage in the cache. (*) fscache_op - Tracks operations being initialised. (*) fscache_wrote_page - Tracks return of the backend write_page op. (*) fscache_gang_lookup - Tracks lookup of pages to be stored in the write operation. Signed-off-by: David Howells <dhowells@redhat.com>
2018-04-04fscache: Add tracepointsDavid Howells1-17/+29
Add some tracepoints to fscache: (*) fscache_cookie - Tracks a cookie's usage count. (*) fscache_netfs - Logs registration of a network filesystem, including the pointer to the cookie allocated. (*) fscache_acquire - Logs cookie acquisition. (*) fscache_relinquish - Logs cookie relinquishment. (*) fscache_enable - Logs enablement of a cookie. (*) fscache_disable - Logs disablement of a cookie. (*) fscache_osm - Tracks execution of states in the object state machine. and cachefiles: (*) cachefiles_ref - Tracks a cachefiles object's usage count. (*) cachefiles_lookup - Logs result of lookup_one_len(). (*) cachefiles_mkdir - Logs result of vfs_mkdir(). (*) cachefiles_create - Logs result of vfs_create(). (*) cachefiles_unlink - Logs calls to vfs_unlink(). (*) cachefiles_rename - Logs calls to vfs_rename(). (*) cachefiles_mark_active - Logs an object becoming active. (*) cachefiles_wait_active - Logs a wait for an old object to be destroyed. (*) cachefiles_mark_inactive - Logs an object becoming inactive. (*) cachefiles_mark_buried - Logs the burial of an object. Signed-off-by: David Howells <dhowells@redhat.com>
2018-04-04fscache: Detect multiple relinquishment of a cookieDavid Howells1-1/+2
Report if an fscache cookie is relinquished multiple times by the netfs. Signed-off-by: David <dhowells@redhat.com>
2018-03-20sched/wait, fs/fscache: Convert wait_on_atomic_t() usage to the new ↵Peter Zijlstra1-3/+4
wait_var_event() API The old wait_on_atomic_t() is going to get removed, use the more flexible wait_var_event() API instead. No change in functionality. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: David Howells <dhowells@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-11-13Pass mode to wait_on_atomic_t() action funcs and provide default actionsDavid Howells1-1/+1
Make wait_on_atomic_t() pass the TASK_* mode onto its action function as an extra argument and make it 'unsigned int throughout. Also, consolidate a bunch of identical action functions into a default function that can do the appropriate thing for the mode. Also, change the argument name in the bit_wait*() function declarations to reflect the fact that it's the mode and not the bit number. [Peter Z gives this a grudging ACK, but thinks that the whole atomic_t wait should be done differently, though he's not immediately sure as to how] Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Peter Zijlstra <peterz@infradead.org> cc: Ingo Molnar <mingo@kernel.org>
2017-01-31fscache: Clear outstanding writes when disabling a cookieDavid Howells1-0/+5
fscache_disable_cookie() needs to clear the outstanding writes on the cookie it's disabling because they cannot be completed after. Without this, fscache_nfs_open_file() gets stuck because it disables the cookie when the file is opened for writing but can't uncache the pages till afterwards - otherwise there's a race between the open routine and anyone who already has it open R/O and is still reading from it. Looking in /proc/pid/stack of the offending process shows: [<ffffffffa0142883>] __fscache_wait_on_page_write+0x82/0x9b [fscache] [<ffffffffa014336e>] __fscache_uncache_all_inode_pages+0x91/0xe1 [fscache] [<ffffffffa01740fa>] nfs_fscache_open_file+0x59/0x9e [nfs] [<ffffffffa01ccf41>] nfs4_file_open+0x17f/0x1b8 [nfsv4] [<ffffffff8117350e>] do_dentry_open+0x16d/0x2b7 [<ffffffff811743ac>] vfs_open+0x5c/0x65 [<ffffffff81184185>] path_openat+0x785/0x8fb [<ffffffff81184343>] do_filp_open+0x48/0x9e [<ffffffff81174710>] do_sys_open+0x13b/0x1cb [<ffffffff811747b9>] SyS_open+0x19/0x1b [<ffffffff81001c44>] do_syscall_64+0x80/0x17a [<ffffffff8165c2da>] return_from_SYSCALL_64+0x0/0x7a [<ffffffffffffffff>] 0xffffffffffffffff Reported-by: Jianhong Yin <jiyin@redhat.com> Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Jeff Layton <jlayton@redhat.com> Acked-by: Steve Dickson <steved@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-11-07mm, page_alloc: distinguish between being unable to sleep, unwilling to ↵Mel Gorman1-1/+1
sleep and avoiding waking kswapd __GFP_WAIT has been used to identify atomic context in callers that hold spinlocks or are in interrupts. They are expected to be high priority and have access one of two watermarks lower than "min" which can be referred to as the "atomic reserve". __GFP_HIGH users get access to the first lower watermark and can be called the "high priority reserve". Over time, callers had a requirement to not block when fallback options were available. Some have abused __GFP_WAIT leading to a situation where an optimisitic allocation with a fallback option can access atomic reserves. This patch uses __GFP_ATOMIC to identify callers that are truely atomic, cannot sleep and have no alternative. High priority users continue to use __GFP_HIGH. __GFP_DIRECT_RECLAIM identifies callers that can sleep and are willing to enter direct reclaim. __GFP_KSWAPD_RECLAIM to identify callers that want to wake kswapd for background reclaim. __GFP_WAIT is redefined as a caller that is willing to enter direct reclaim and wake kswapd for background reclaim. This patch then converts a number of sites o __GFP_ATOMIC is used by callers that are high priority and have memory pools for those requests. GFP_ATOMIC uses this flag. o Callers that have a limited mempool to guarantee forward progress clear __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall into this category where kswapd will still be woken but atomic reserves are not used as there is a one-entry mempool to guarantee progress. o Callers that are checking if they are non-blocking should use the helper gfpflags_allow_blocking() where possible. This is because checking for __GFP_WAIT as was done historically now can trigger false positives. Some exceptions like dm-crypt.c exist where the code intent is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to flag manipulations. o Callers that built their own GFP flags instead of starting with GFP_KERNEL and friends now also need to specify __GFP_KSWAPD_RECLAIM. The first key hazard to watch out for is callers that removed __GFP_WAIT and was depending on access to atomic reserves for inconspicuous reasons. In some cases it may be appropriate for them to use __GFP_HIGH. The second key hazard is callers that assembled their own combination of GFP flags instead of starting with something like GFP_KERNEL. They may now wish to specify __GFP_KSWAPD_RECLAIM. It's almost certainly harmless if it's missed in most cases as other activity will wake kswapd. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-02FS-Cache: The operation cancellation method needs calling in more placesDavid Howells1-3/+2
Any time an incomplete operation is cancelled, the operation cancellation function needs to be called to clean up. This is currently being passed directly to some of the functions that might want to call it, but not all. Instead, pass the cancellation method pointer to the fscache_operation_init() and have that cache it in the operation struct. Further, plug in a dummy cancellation handler if the caller declines to set one as this allows us to call the function unconditionally (the extra overhead isn't worth bothering about as we don't expect to be calling this typically). The cancellation method must thence be called everywhere the CANCELLED state is set. Note that we call it *before* setting the CANCELLED state such that the method can use the old state value to guide its operation. fscache_do_cancel_retrieval() needs moving higher up in the sources so that the init function can use it now. Without this, the following oops may be seen: FS-Cache: Assertion failed FS-Cache: 3 == 0 is false ------------[ cut here ]------------ kernel BUG at ../fs/fscache/page.c:261! ... RIP: 0010:[<ffffffffa0089c1b>] fscache_release_retrieval_op+0x77/0x100 [<ffffffffa008853d>] fscache_put_operation+0x114/0x2da [<ffffffffa008b8c2>] __fscache_read_or_alloc_pages+0x358/0x3b3 [<ffffffffa00b761f>] __nfs_readpages_from_fscache+0x59/0xbf [nfs] [<ffffffffa00b06c5>] nfs_readpages+0x10c/0x185 [nfs] [<ffffffff81124925>] ? alloc_pages_current+0x119/0x13e [<ffffffff810ee5fd>] ? __page_cache_alloc+0xfb/0x10a [<ffffffff810f87f8>] __do_page_cache_readahead+0x188/0x22c [<ffffffff810f8b3a>] ondemand_readahead+0x29e/0x2af [<ffffffff810f8c92>] page_cache_sync_readahead+0x38/0x3a [<ffffffff810ef337>] generic_file_read_iter+0x1a2/0x55a [<ffffffffa00a9dff>] ? nfs_revalidate_mapping+0xd6/0x288 [nfs] [<ffffffffa00a6a23>] nfs_file_read+0x49/0x70 [nfs] [<ffffffff811363be>] new_sync_read+0x78/0x9c [<ffffffff81137164>] __vfs_read+0x13/0x38 [<ffffffff8113721e>] vfs_read+0x95/0x121 [<ffffffff811372f6>] SyS_read+0x4c/0x8a [<ffffffff81557a52>] system_call_fastpath+0x12/0x17 The assertion is showing that the remaining number of pages (n_pages) is not 0 when the operation is being released. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Steve Dickson <steved@redhat.com> Acked-by: Jeff Layton <jeff.layton@primarydata.com>
2015-04-02FS-Cache: fscache_object_is_dead() has wrong logic, kill itDavid Howells1-1/+2
fscache_object_is_dead() returns true only if the object is marked dead and the cache got an I/O error. This should be a logical OR instead. Since two of the callers got split up into handling for separate subcases, expand the other callers and kill the function. This is probably the right thing to do anyway since one of the subcases isn't about the object at all, but rather about the cache. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Steve Dickson <steved@redhat.com> Acked-by: Jeff Layton <jeff.layton@primarydata.com>
2014-07-16sched: Remove proliferation of wait_on_bit() action functionsNeilBrown1-4/+3
The current "wait_on_bit" interface requires an 'action' function to be provided which does the actual waiting. There are over 20 such functions, many of them identical. Most cases can be satisfied by one of just two functions, one which uses io_schedule() and one which just uses schedule(). So: Rename wait_on_bit and wait_on_bit_lock to wait_on_bit_action and wait_on_bit_lock_action to make it explicit that they need an action function. Introduce new wait_on_bit{,_lock} and wait_on_bit{,_lock}_io which are *not* given an action function but implicitly use a standard one. The decision to error-out if a signal is pending is now made based on the 'mode' argument rather than being encoded in the action function. All instances of the old wait_on_bit and wait_on_bit_lock which can use the new version have been changed accordingly and their action functions have been discarded. wait_on_bit{_lock} does not return any specific error code in the event of a signal so the caller must check for non-zero and interpolate their own error code as appropriate. The wait_on_bit() call in __fscache_wait_on_invalidate() was ambiguous as it specified TASK_UNINTERRUPTIBLE but used fscache_wait_bit_interruptible as an action function. David Howells confirms this should be uniformly "uninterruptible" The main remaining user of wait_on_bit{,_lock}_action is NFS which needs to use a freezer-aware schedule() call. A comment in fs/gfs2/glock.c notes that having multiple 'action' functions is useful as they display differently in the 'wchan' field of 'ps'. (and /proc/$PID/wchan). As the new bit_wait{,_io} functions are tagged "__sched", they will not show up at all, but something higher in the stack. So the distinction will still be visible, only with different function names (gds2_glock_wait versus gfs2_glock_dq_wait in the gfs2/glock.c case). Since first version of this patch (against 3.15) two new action functions appeared, on in NFS and one in CIFS. CIFS also now uses an action function that makes the same freezer aware schedule call as NFS. Signed-off-by: NeilBrown <neilb@suse.de> Acked-by: David Howells <dhowells@redhat.com> (fscache, keys) Acked-by: Steven Whitehouse <swhiteho@redhat.com> (gfs2) Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Steve French <sfrench@samba.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20140707051603.28027.72349.stgit@notabene.brown Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-06-05fs/fscache: convert printk to pr_foo()Fabian Frederick1-1/+1
All printk converted to pr_foo() except internal.h: printk(KERN_DEBUG Coalesce formats. Add pr_fmt Signed-off-by: Fabian Frederick <fabf@skynet.be> Cc: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-09-27FS-Cache: Provide the ability to enable/disable cookiesDavid Howells1-49/+137
Provide the ability to enable and disable fscache cookies. A disabled cookie will reject or ignore further requests to: Acquire a child cookie Invalidate and update backing objects Check the consistency of a backing object Allocate storage for backing page Read backing pages Write to backing pages but still allows: Checks/waits on the completion of already in-progress objects Uncaching of pages Relinquishment of cookies Two new operations are provided: (1) Disable a cookie: void fscache_disable_cookie(struct fscache_cookie *cookie, bool invalidate); If the cookie is not already disabled, this locks the cookie against other dis/enablement ops, marks the cookie as being disabled, discards or invalidates any backing objects and waits for cessation of activity on any associated object. This is a wrapper around a chunk split out of fscache_relinquish_cookie(), but it reinitialises the cookie such that it can be reenabled. All possible failures are handled internally. The caller should consider calling fscache_uncache_all_inode_pages() afterwards to make sure all page markings are cleared up. (2) Enable a cookie: void fscache_enable_cookie(struct fscache_cookie *cookie, bool (*can_enable)(void *data), void *data) If the cookie is not already enabled, this locks the cookie against other dis/enablement ops, invokes can_enable() and, if the cookie is not an index cookie, will begin the procedure of acquiring backing objects. The optional can_enable() function is passed the data argument and returns a ruling as to whether or not enablement should actually be permitted to begin. All possible failures are handled internally. The cookie will only be marked as enabled if provisional backing objects are allocated. A later patch will introduce these to NFS. Cookie enablement during nfs_open() is then contingent on i_writecount <= 0. can_enable() checks for a race between open(O_RDONLY) and open(O_WRONLY/O_RDWR). This simplifies NFS's cookie handling and allows us to get rid of open(O_RDONLY) accidentally introducing caching to an inode that's open for writing already. One operation has its API modified: (3) Acquire a cookie. struct fscache_cookie *fscache_acquire_cookie( struct fscache_cookie *parent, const struct fscache_cookie_def *def, void *netfs_data, bool enable); This now has an additional argument that indicates whether the requested cookie should be enabled by default. It doesn't need the can_enable() function because the caller must prevent multiple calls for the same netfs object and it doesn't need to take the enablement lock because no one else can get at the cookie before this returns. Signed-off-by: David Howells <dhowells@redhat.com
2013-09-27FS-Cache: Add use/unuse/wake cookie wrappersDavid Howells1-2/+5
Add wrapper functions for dealing with cookie->n_active: (*) __fscache_use_cookie() to increment it. (*) __fscache_unuse_cookie() to decrement and test against zero. (*) __fscache_wake_unused_cookie() to wake up anyone waiting for it to reach zero. The second and third are split so that the third can be done after cookie->lock has been released in case the waiter wakes up whilst we're still holding it and tries to get it. We will need to wake-on-zero once the cookie disablement patch is applied because it will then be possible to see n_active become zero without the cookie being relinquished. Also move the cookie usement out of fscache_attr_changed_op() and into fscache_attr_changed() and the operation struct so that cookie disablement will be able to track it. Whilst we're at it, only increment n_active if we're about to do fscache_submit_op() so that we don't have to deal with undoing it if anything earlier fails. Possibly this should be moved into fscache_submit_op() which could look at FSCACHE_OP_UNUSE_COOKIE. Signed-off-by: David Howells <dhowells@redhat.com>
2013-09-10fscache: check consistency does not decrement refcountMilosz Tanski1-1/+2
__fscache_check_consistency() does not decrement the count of operations active after it finishes in the success case. This leads to a hung tasks on cookie de-registration (commonly in inode eviction). INFO: task kworker/1:2:4214 blocked for more than 120 seconds. kworker/1:2 D ffff880443513fc0 0 4214 2 0x00000000 Workqueue: ceph-msgr con_work [libceph] ... Call Trace: [<ffffffff81569fc6>] ? _raw_spin_unlock_irqrestore+0x16/0x20 [<ffffffffa0016570>] ? fscache_wait_bit_interruptible+0x30/0x30 [fscache] [<ffffffff81568d09>] schedule+0x29/0x70 [<ffffffffa001657e>] fscache_wait_atomic_t+0xe/0x20 [fscache] [<ffffffff815665cf>] out_of_line_wait_on_atomic_t+0x9f/0xe0 [<ffffffff81083560>] ? autoremove_wake_function+0x40/0x40 [<ffffffffa0015a9c>] __fscache_relinquish_cookie+0x15c/0x310 [fscache] [<ffffffffa00a4fae>] ceph_fscache_unregister_inode_cookie+0x3e/0x50 [ceph] [<ffffffffa007e373>] ceph_destroy_inode+0x33/0x200 [ceph] [<ffffffff811c13ae>] ? __fsnotify_inode_delete+0xe/0x10 [<ffffffff8119ba1c>] destroy_inode+0x3c/0x70 [<ffffffff8119bb69>] evict+0x119/0x1b0 Signed-off-by: Milosz Tanski <milosz@adfin.com> Acked-by: David Howells <dhowells@redhat.com> Signed-off-by: Sage Weil <sage@inktank.com>
2013-09-06FS-Cache: Add interface to check consistency of a cached objectDavid Howells1-0/+71
Extend the fscache netfs API so that the netfs can ask as to whether a cache object is up to date with respect to its corresponding netfs object: int fscache_check_consistency(struct fscache_cookie *cookie) This will call back to the netfs to check whether the auxiliary data associated with a cookie is correct. It returns 0 if it is and -ESTALE if it isn't; it may also return -ENOMEM and -ERESTARTSYS. The backends now have to implement a mandatory operation pointer: int (*check_consistency)(struct fscache_object *object) that corresponds to the above API call. FS-Cache takes care of pinning the object and the cookie in memory and managing this call with respect to the object state. Original-author: Hongyi Jia <jiayisuse@gmail.com> Signed-off-by: David Howells <dhowells@redhat.com> cc: Hongyi Jia <jiayisuse@gmail.com> cc: Milosz Tanski <milosz@adfin.com>
2013-06-19FS-Cache: Simplify cookie retention for fscache_objects, fixing oopsDavid Howells1-54/+26
Simplify the way fscache cache objects retain their cookie. The way I implemented the cookie storage handling made synchronisation a pain (ie. the object state machine can't rely on the cookie actually still being there). Instead of the the object being detached from the cookie and the cookie being freed in __fscache_relinquish_cookie(), we defer both operations: (*) The detachment of the object from the list in the cookie now takes place in fscache_drop_object() and is thus governed by the object state machine (fscache_detach_from_cookie() has been removed). (*) The release of the cookie is now in fscache_object_destroy() - which is called by the cache backend just before it frees the object. This means that the fscache_cookie struct is now available to the cache all the way through from ->alloc_object() to ->drop_object() and ->put_object() - meaning that it's no longer necessary to take object->lock to guarantee access. However, __fscache_relinquish_cookie() doesn't wait for the object to go all the way through to destruction before letting the netfs proceed. That would massively slow down the netfs. Since __fscache_relinquish_cookie() leaves the cookie around, in must therefore break all attachments to the netfs - which includes ->def, ->netfs_data and any outstanding page read/writes. To handle this, struct fscache_cookie now has an n_active counter: (1) This starts off initialised to 1. (2) Any time the cache needs to get at the netfs data, it calls fscache_use_cookie() to increment it - if it is not zero. If it was zero, then access is not permitted. (3) When the cache has finished with the data, it calls fscache_unuse_cookie() to decrement it. This does a wake-up on it if it reaches 0. (4) __fscache_relinquish_cookie() decrements n_active and then waits for it to reach 0. The initialisation to 1 in step (1) ensures that we only get wake ups when we're trying to get rid of the cookie. This leaves __fscache_relinquish_cookie() a lot simpler. *** This fixes a problem in the current code whereby if fscache_invalidate() is followed sufficiently quickly by fscache_relinquish_cookie() then it is possible for __fscache_relinquish_cookie() to have detached the cookie from the object and cleared the pointer before a thread is dispatched to process the invalidation state in the object state machine. Since the pending write clearance was deferred to the invalidation state to make it asynchronous, we need to either wait in relinquishment for the stores tree to be cleared in the invalidation state or we need to handle the clearance in relinquishment. Further, if the relinquishment code does clear the tree, then the invalidation state need to make the clearance contingent on still having the cookie to hand (since that's where the tree is rooted) and we have to prevent the cookie from disappearing for the duration. This can lead to an oops like the following: BUG: unable to handle kernel NULL pointer dereference at 000000000000000c ... RIP: 0010:[<ffffffff8151023e>] _spin_lock+0xe/0x30 ... CR2: 000000000000000c ... ... Process kslowd002 (...) .... Call Trace: [<ffffffffa01c3278>] fscache_invalidate_writes+0x38/0xd0 [fscache] [<ffffffff810096f0>] ? __switch_to+0xd0/0x320 [<ffffffff8105e759>] ? find_busiest_queue+0x69/0x150 [<ffffffff8110ddd4>] ? slow_work_enqueue+0x104/0x180 [<ffffffffa01c1303>] fscache_object_slow_work_execute+0x5e3/0x9d0 [fscache] [<ffffffff81096b67>] ? bit_waitqueue+0x17/0xd0 [<ffffffff8110e233>] slow_work_execute+0x233/0x310 [<ffffffff8110e515>] slow_work_thread+0x205/0x360 [<ffffffff81096ca0>] ? autoremove_wake_function+0x0/0x40 [<ffffffff8110e310>] ? slow_work_thread+0x0/0x360 [<ffffffff81096936>] kthread+0x96/0xa0 [<ffffffff8100c0ca>] child_rip+0xa/0x20 [<ffffffff810968a0>] ? kthread+0x0/0xa0 [<ffffffff8100c0c0>] ? child_rip+0x0/0x20 The parameter to fscache_invalidate_writes() was object->cookie which is NULL. Signed-off-by: David Howells <dhowells@redhat.com> Tested-By: Milosz Tanski <milosz@adfin.com> Acked-by: Jeff Layton <jlayton@redhat.com>
2013-06-19FS-Cache: Fix object state machine to have separate work and wait statesDavid Howells1-5/+4
Fix object state machine to have separate work and wait states as that makes it easier to envision. There are now three kinds of state: (1) Work state. This is an execution state. No event processing is performed by a work state. The function attached to a work state returns a pointer indicating the next state to which the OSM should transition. Returning NO_TRANSIT repeats the current state, but goes back to the scheduler first. (2) Wait state. This is an event processing state. No execution is performed by a wait state. Wait states are just tables of "if event X occurs, clear it and transition to state Y". The dispatcher returns to the scheduler if none of the events in which the wait state has an interest are currently pending. (3) Out-of-band state. This is a special work state. Transitions to normal states can be overridden when an unexpected event occurs (eg. I/O error). Instead the dispatcher disables and clears the OOB event and transits to the specified work state. This then acts as an ordinary work state, though object->state points to the overridden destination. Returning NO_TRANSIT resumes the overridden transition. In addition, the states have names in their definitions, so there's no need for tables of state names. Further, the EV_REQUEUE event is no longer necessary as that is automatic for work states. Since the states are now separate structs rather than values in an enum, it's not possible to use comparisons other than (non-)equality between them, so use some object->flags to indicate what phase an object is in. The EV_RELEASE, EV_RETIRE and EV_WITHDRAW events have been squished into one (EV_KILL). An object flag now carries the information about retirement. Similarly, the RELEASING, RECYCLING and WITHDRAWING states have been merged into an KILL_OBJECT state and additional states have been added for handling waiting dependent objects (JUMPSTART_DEPS and KILL_DEPENDENTS). A state has also been added for synchronising with parent object initialisation (WAIT_FOR_PARENT) and another for initiating look up (PARENT_READY). Signed-off-by: David Howells <dhowells@redhat.com> Tested-By: Milosz Tanski <milosz@adfin.com> Acked-by: Jeff Layton <jlayton@redhat.com>
2013-06-19FS-Cache: Wrap checks on object stateDavid Howells1-4/+4
Wrap checks on object state (mostly outside of fs/fscache/object.c) with inline functions so that the mechanism can be replaced. Some of the state checks within object.c are left as-is as they will be replaced. Signed-off-by: David Howells <dhowells@redhat.com> Tested-By: Milosz Tanski <milosz@adfin.com> Acked-by: Jeff Layton <jlayton@redhat.com>
2013-02-28hlist: drop the node parameter from iteratorsSasha Levin1-7/+4
I'm not sure why, but the hlist for each entry iterators were conceived list_for_each_entry(pos, head, member) The hlist ones were greedy and wanted an extra parameter: hlist_for_each_entry(tpos, pos, head, member) Why did they need an extra pos parameter? I'm not quite sure. Not only they don't really need it, it also prevents the iterator from looking exactly like the list iterator, which is unfortunate. Besides the semantic patch, there was some manual work required: - Fix up the actual hlist iterators in linux/list.h - Fix up the declaration of other iterators based on the hlist ones. - A very small amount of places were using the 'node' parameter, this was modified to use 'obj->member' instead. - Coccinelle didn't handle the hlist_for_each_entry_safe iterator properly, so those had to be fixed up manually. The semantic patch which is mostly the work of Peter Senna Tschudin is here: @@ iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host; type T; expression a,c,d,e; identifier b; statement S; @@ -T b; <+... when != b ( hlist_for_each_entry(a, - b, c, d) S | hlist_for_each_entry_continue(a, - b, c) S | hlist_for_each_entry_from(a, - b, c) S | hlist_for_each_entry_rcu(a, - b, c, d) S | hlist_for_each_entry_rcu_bh(a, - b, c, d) S | hlist_for_each_entry_continue_rcu_bh(a, - b, c) S | for_each_busy_worker(a, c, - b, d) S | ax25_uid_for_each(a, - b, c) S | ax25_for_each(a, - b, c) S | inet_bind_bucket_for_each(a, - b, c) S | sctp_for_each_hentry(a, - b, c) S | sk_for_each(a, - b, c) S | sk_for_each_rcu(a, - b, c) S | sk_for_each_from -(a, b) +(a) S + sk_for_each_from(a) S | sk_for_each_safe(a, - b, c, d) S | sk_for_each_bound(a, - b, c) S | hlist_for_each_entry_safe(a, - b, c, d, e) S | hlist_for_each_entry_continue_rcu(a, - b, c) S | nr_neigh_for_each(a, - b, c) S | nr_neigh_for_each_safe(a, - b, c, d) S | nr_node_for_each(a, - b, c) S | nr_node_for_each_safe(a, - b, c, d) S | - for_each_gfn_sp(a, c, d, b) S + for_each_gfn_sp(a, c, d) S | - for_each_gfn_indirect_valid_sp(a, c, d, b) S + for_each_gfn_indirect_valid_sp(a, c, d) S | for_each_host(a, - b, c) S | for_each_host_safe(a, - b, c, d) S | for_each_mesh_entry(a, - b, c, d) S ) ...+> [akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c] [akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c] [akpm@linux-foundation.org: checkpatch fixes] [akpm@linux-foundation.org: fix warnings] [akpm@linux-foudnation.org: redo intrusive kvm changes] Tested-by: Peter Senna Tschudin <peter.senna@gmail.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Gleb Natapov <gleb@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-21FS-Cache: Provide proper invalidationDavid Howells1-0/+60
Provide a proper invalidation method rather than relying on the netfs retiring the cookie it has and getting a new one. The problem with this is that isn't easy for the netfs to make sure that it has completed/cancelled all its outstanding storage and retrieval operations on the cookie it is retiring. Instead, have the cache provide an invalidation method that will cancel or wait for all currently outstanding operations before invalidating the cache, and will cause new operations to queue up behind that. Whilst invalidation is in progress, some requests will be rejected until the cache can stack a barrier on the operation queue to cause new operations to be deferred behind it. Signed-off-by: David Howells <dhowells@redhat.com>
2012-12-21FS-Cache: Make cookie relinquishment wait for outstanding readsDavid Howells1-4/+14
Make fscache_relinquish_cookie() log a warning and wait if there are any outstanding reads left on the cookie it was given. Signed-off-by: David Howells <dhowells@redhat.com>
2012-12-21FS-Cache: Check that there are no read ops when cookie relinquishedDavid Howells1-0/+8
Check that the netfs isn't trying to relinquish a cookie that still has read operations in progress upon it. If there are, then give log a warning and BUG. Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19FS-Cache: Add a retirement stat counterDavid Howells1-0/+2
Add a stat counter to count retirement events rather than ordinary release events (the retire argument to fscache_relinquish_cookie()). Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19FS-Cache: Fix lock misorder in fscache_write_op()David Howells1-0/+1
FS-Cache has two structs internally for keeping track of the internal state of a cached file: the fscache_cookie struct, which represents the netfs's state, and fscache_object struct, which represents the cache's state. Each has a pointer that points to the other (when both are in existence), and each has a spinlock for pointer maintenance. Since netfs operations approach these structures from the cookie side, they get the cookie lock first, then the object lock. Cache operations, on the other hand, approach from the object side, and get the object lock first. It is not then permitted for a cache operation to get the cookie lock whilst it is holding the object lock lest deadlock occur; instead, it must do one of two things: (1) increment the cookie usage counter, drop the object lock and then get both locks in order, or (2) simply hold the object lock as certain parts of the cookie may not be altered whilst the object lock is held. It is also not permitted to follow either pointer without holding the lock at the end you start with. To break the pointers between the cookie and the object, both locks must be held. fscache_write_op(), however, violates the locking rules: It attempts to get the cookie lock without (a) checking that the cookie pointer is a valid pointer, and (b) holding the object lock to protect the cookie pointer whilst it follows it. This is so that it can access the pending page store tree without interference from __fscache_write_page(). This is fixed by splitting the cookie lock, such that the page store tracking tree is protected by its own lock, and checking that the cookie pointer is non-NULL before we attempt to follow it whilst holding the object lock. The new lock is subordinate to both the cookie lock and the object lock, and so should be taken after those. Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19FS-Cache: Use radix tree preload correctly in tracking of pages to be storedDavid Howells1-1/+3
__fscache_write_page() attempts to load the radix tree preallocation pool for the CPU it is on before calling radix_tree_insert(), as the insertion must be done inside a pair of spinlocks. Use of the preallocation pool, however, is contingent on the radix tree being initialised without __GFP_WAIT specified. __fscache_acquire_cookie() was passing GFP_NOFS to INIT_RADIX_TREE() - but that includes __GFP_WAIT. The solution is to AND out __GFP_WAIT. Additionally, the banner comment to radix_tree_preload() is altered to make note of this prerequisite. Possibly there should be a WARN_ON() too. Without this fix, I have seen the following recursive deadlock caused by radix_tree_insert() attempting to allocate memory inside the spinlocked region, which resulted in FS-Cache being called back into to release memory - which required the spinlock already held. ============================================= [ INFO: possible recursive locking detected ] 2.6.32-rc6-cachefs #24 --------------------------------------------- nfsiod/7916 is trying to acquire lock: (&cookie->lock){+.+.-.}, at: [<ffffffffa0076872>] __fscache_uncache_page+0xdb/0x160 [fscache] but task is already holding lock: (&cookie->lock){+.+.-.}, at: [<ffffffffa0076acc>] __fscache_write_page+0x15c/0x3f3 [fscache] other info that might help us debug this: 5 locks held by nfsiod/7916: #0: (nfsiod){+.+.+.}, at: [<ffffffff81048290>] worker_thread+0x19a/0x2e2 #1: (&task->u.tk_work#2){+.+.+.}, at: [<ffffffff81048290>] worker_thread+0x19a/0x2e2 #2: (&cookie->lock){+.+.-.}, at: [<ffffffffa0076acc>] __fscache_write_page+0x15c/0x3f3 [fscache] #3: (&object->lock#2){+.+.-.}, at: [<ffffffffa0076b07>] __fscache_write_page+0x197/0x3f3 [fscache] #4: (&cookie->stores_lock){+.+...}, at: [<ffffffffa0076b0f>] __fscache_write_page+0x19f/0x3f3 [fscache] stack backtrace: Pid: 7916, comm: nfsiod Not tainted 2.6.32-rc6-cachefs #24 Call Trace: [<ffffffff8105ac7f>] __lock_acquire+0x1649/0x16e3 [<ffffffff81059ded>] ? __lock_acquire+0x7b7/0x16e3 [<ffffffff8100e27d>] ? dump_trace+0x248/0x257 [<ffffffff8105ad70>] lock_acquire+0x57/0x6d [<ffffffffa0076872>] ? __fscache_uncache_page+0xdb/0x160 [fscache] [<ffffffff8135467c>] _spin_lock+0x2c/0x3b [<ffffffffa0076872>] ? __fscache_uncache_page+0xdb/0x160 [fscache] [<ffffffffa0076872>] __fscache_uncache_page+0xdb/0x160 [fscache] [<ffffffffa0077eb7>] ? __fscache_check_page_write+0x0/0x71 [fscache] [<ffffffffa00b4755>] nfs_fscache_release_page+0x86/0xc4 [nfs] [<ffffffffa00907f0>] nfs_release_page+0x3c/0x41 [nfs] [<ffffffff81087ffb>] try_to_release_page+0x32/0x3b [<ffffffff81092c2b>] shrink_page_list+0x316/0x4ac [<ffffffff81058a9b>] ? mark_held_locks+0x52/0x70 [<ffffffff8135451b>] ? _spin_unlock_irq+0x2b/0x31 [<ffffffff81093153>] shrink_inactive_list+0x392/0x67c [<ffffffff81058a9b>] ? mark_held_locks+0x52/0x70 [<ffffffff810934ca>] shrink_list+0x8d/0x8f [<ffffffff81093744>] shrink_zone+0x278/0x33c [<ffffffff81052c70>] ? ktime_get_ts+0xad/0xba [<ffffffff8109453b>] try_to_free_pages+0x22e/0x392 [<ffffffff8109184c>] ? isolate_pages_global+0x0/0x212 [<ffffffff8108e16b>] __alloc_pages_nodemask+0x3dc/0x5cf [<ffffffff810ae24a>] cache_alloc_refill+0x34d/0x6c1 [<ffffffff811bcf74>] ? radix_tree_node_alloc+0x52/0x5c [<ffffffff810ae929>] kmem_cache_alloc+0xb2/0x118 [<ffffffff811bcf74>] radix_tree_node_alloc+0x52/0x5c [<ffffffff811bcfd5>] radix_tree_insert+0x57/0x19c [<ffffffffa0076b53>] __fscache_write_page+0x1e3/0x3f3 [fscache] [<ffffffffa00b4248>] __nfs_readpage_to_fscache+0x58/0x11e [nfs] [<ffffffffa009bb77>] nfs_readpage_release+0x34/0x9b [nfs] [<ffffffffa009c0d9>] nfs_readpage_release_full+0x32/0x4b [nfs] [<ffffffffa0006cff>] rpc_release_calldata+0x12/0x14 [sunrpc] [<ffffffffa0006e2d>] rpc_free_task+0x59/0x61 [sunrpc] [<ffffffffa0006f03>] rpc_async_release+0x10/0x12 [sunrpc] [<ffffffff810482e5>] worker_thread+0x1ef/0x2e2 [<ffffffff81048290>] ? worker_thread+0x19a/0x2e2 [<ffffffff81352433>] ? thread_return+0x3e/0x101 [<ffffffffa0006ef3>] ? rpc_async_release+0x0/0x12 [sunrpc] [<ffffffff8104bff5>] ? autoremove_wake_function+0x0/0x34 [<ffffffff81058d25>] ? trace_hardirqs_on+0xd/0xf [<ffffffff810480f6>] ? worker_thread+0x0/0x2e2 [<ffffffff8104bd21>] kthread+0x7a/0x82 [<ffffffff8100beda>] child_rip+0xa/0x20 [<ffffffff8100b87c>] ? restore_args+0x0/0x30 [<ffffffff8104c2b9>] ? add_wait_queue+0x15/0x44 [<ffffffff8104bca7>] ? kthread+0x0/0x82 [<ffffffff8100bed0>] ? child_rip+0x0/0x20 Signed-off-by: David Howells <dhowells@redhat.com>
2009-11-19FS-Cache: Clear netfs pointers in cookie after detaching object, not beforeDavid Howells1-4/+4
Clear the pointers from the fscache_cookie struct to netfs private data after clearing the pointer to the cookie from the fscache_object struct and releasing the object lock, rather than before. This allows the netfs private data pointers to be relied on simply by holding the object lock, rather than having to hold the cookie lock. This is makes things simpler as the cookie lock has to be taken before the object lock, but sometimes the object pointer is all that the code has. Signed-off-by: David Howells <dhowells@redhat.com>
generated by cgit v1.2.3 (git 2.39.0) at 2024-11-25 14:51:26 +0300