linux/fs/cachefiles, branch v3.12

CacheFiles: Don't try to dump the index key if the cookie has been cleared

2013-09-20T22:15:43Z

Don't try to dump the index key that distinguishes an object if netfs data in the cookie the object refers to has been cleared (ie. the cookie has passed most of the way through __fscache_relinquish_cookie()). Since the netfs holds the index key, we can't get at it once the ->def and ->netfs_data pointers have been cleared - and a NULL pointer exception will ensue, usually just after a: CacheFiles: Error: Unexpected object collision error is reported. Signed-off-by: David Howells Signed-off-by: Linus Torvalds

CacheFiles: Fix memory leak in cachefiles_check_auxdata error paths

2013-09-20T22:15:42Z

In cachefiles_check_auxdata(), we allocate auxbuf but fail to free it if we determine there's an error or that the data is stale. Further, assigning the output of vfs_getxattr() to auxbuf->len gives problems with checking for errors as auxbuf->len is a u16. We don't actually need to set auxbuf->len, so keep the length in a variable for now. We shouldn't need to check the upper limit of the buffer as an overflow there should be indicated by -ERANGE. While we're at it, fscache_check_aux() returns an enum value, not an int, so assign it to an appropriately typed variable rather than to ret. Signed-off-by: Josh Boyer Signed-off-by: David Howells cc: Hongyi Jia cc: Milosz Tanski Signed-off-by: Linus Torvalds

CacheFiles: Implement interface to check cache consistency

2013-09-06T08:17:30Z

Implement the FS-Cache interface to check the consistency of a cache object in CacheFiles. Original-author: Hongyi Jia Signed-off-by: David Howells cc: Hongyi Jia cc: Milosz Tanski

mm: remove lru parameter from __pagevec_lru_add and remove parts of pagevec API

2013-07-03T23:07:31Z

Now that the LRU to add a page to is decided at LRU-add time, remove the misleading lru parameter from __pagevec_lru_add. A consequence of this is that the pagevec_lru_add_file, pagevec_lru_add_anon and similar helpers are misleading as the caller no longer has direct control over what LRU the page is added to. Unused helpers are removed by this patch and existing users of pagevec_lru_add_file() are converted to use lru_cache_add_file() directly and use the per-cpu pagevecs instead of creating their own pagevec. Signed-off-by: Mel Gorman Reviewed-by: Jan Kara Reviewed-by: Rik van Riel Acked-by: Johannes Weiner Cc: Alexey Lyahkov Cc: Andrew Perepechko Cc: Robin Dong Cc: Theodore Tso Cc: Hugh Dickins Cc: Rik van Riel Cc: Bernd Schubert Cc: David Howells Cc: Trond Myklebust Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

cachefiles: remove unused macro list_to_page()

2013-06-19T13:16:47Z

Signed-off-by: Haicheng Li Signed-off-by: David Howells Tested-By: Milosz Tanski Acked-by: Jeff Layton

FS-Cache: Simplify cookie retention for fscache_objects, fixing oops

2013-06-19T13:16:47Z

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:[] _spin_lock+0xe/0x30 ... CR2: 000000000000000c ... ... Process kslowd002 (...) .... Call Trace: [] fscache_invalidate_writes+0x38/0xd0 [fscache] [] ? __switch_to+0xd0/0x320 [] ? find_busiest_queue+0x69/0x150 [] ? slow_work_enqueue+0x104/0x180 [] fscache_object_slow_work_execute+0x5e3/0x9d0 [fscache] [] ? bit_waitqueue+0x17/0xd0 [] slow_work_execute+0x233/0x310 [] slow_work_thread+0x205/0x360 [] ? autoremove_wake_function+0x0/0x40 [] ? slow_work_thread+0x0/0x360 [] kthread+0x96/0xa0 [] child_rip+0xa/0x20 [] ? kthread+0x0/0xa0 [] ? child_rip+0x0/0x20 The parameter to fscache_invalidate_writes() was object->cookie which is NULL. Signed-off-by: David Howells Tested-By: Milosz Tanski Acked-by: Jeff Layton

FS-Cache: Fix object state machine to have separate work and wait states

2013-06-19T13:16:47Z

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 Tested-By: Milosz Tanski Acked-by: Jeff Layton

FS-Cache: Wrap checks on object state

2013-06-19T13:16:47Z

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 Tested-By: Milosz Tanski Acked-by: Jeff Layton

CacheFiles: name i_mutex lock class explicitly

2013-06-19T13:16:47Z

Just some cleanup. (And note the caller of this function may, for example, call vfs_unlink on a child, so the "1" (I_MUTEX_PARENT) really was what was intended here.) Signed-off-by: J. Bruce Fields Signed-off-by: David Howells Tested-By: Milosz Tanski Acked-by: Jeff Layton

lift sb_start_write() out of ->write()

2013-04-09T18:12:56Z

Signed-off-by: Al Viro