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path: root/drivers/md/dm-snap.c
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* dm snapshot: extend exception store functionsJonathan Brassow2009-01-05
| | | | | | | | | Supply dm_add_exception as a callback to the read_metadata function. Add a status function ready for a later patch and name the functions consistently. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: split out exception store implementationsAlasdair G Kergon2009-01-05
| | | | | | | | Move the existing snapshot exception store implementations out into separate files. Later patches will place these behind a new interface in preparation for alternative implementations. Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: separate out exception store interfaceJonathan Brassow2009-01-05
| | | | | | | | | | | | | Pull structures that bridge the gap between snapshot and exception store out of dm-snap.h and put them in a new .h file - dm-exception-store.h. This file will define the API for new exception stores. Ultimately, dm-snap.h is unnecessary, since only dm-snap.c should be using it. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: consolidate target deregistration error handlingMikulas Patocka2009-01-05
| | | | | | | | | | | | | | | | | | | | Change dm_unregister_target to return void and use BUG() for error reporting. dm_unregister_target can only fail because of programming bug in the target driver. It can't fail because of user's behavior or disk errors. This patch changes unregister_target to return void and use BUG if someone tries to unregister non-registered target or unregister target that is in use. This patch removes code duplication (testing of error codes in all dm targets) and reports bugs in just one place, in dm_unregister_target. In some target drivers, these return codes were ignored, which could lead to a situation where bugs could be missed. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: change yield to msleepMikulas Patocka2009-01-05
| | | | | | | | | Change yield() to msleep(1). If the thread had realtime priority, yield() doesn't really yield, so the yielding process would loop indefinitely and cause machine lockup. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: wait for chunks in destructorMikulas Patocka2008-10-30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If there are several snapshots sharing an origin and one is removed while the origin is being written to, the snapshot's mempool may get deleted while elements are still referenced. Prior to dm-snapshot-use-per-device-mempools.patch the pending exceptions may still have been referenced after the snapshot was destroyed, but this was not a problem because the shared mempool was still there. This patch fixes the problem by tracking the number of mempool elements in use. The scenario: - You have an origin and two snapshots 1 and 2. - Someone writes to the origin. - It creates two exceptions in the snapshots, snapshot 1 will be primary exception, snapshot 2's pending_exception->primary_pe will point to the exception in snapshot 1. - The exceptions are being relocated, relocation of exception 1 finishes (but it's pending_exception is still allocated, because it is referenced by an exception from snapshot 2) - The user lvremoves snapshot 1 --- it calls just suspend (does nothing) and destructor. md->pending is zero (there is no I/O submitted to the snapshot by md layer), so it won't help us. - The destructor waits for kcopyd jobs to finish on snapshot 1 --- but there are none. - The destructor on snapshot 1 cleans up everything. - The relocation of exception on snapshot 2 finishes, it drops reference on primary_pe. This frees its primary_pe pointer. Primary_pe points to pending exception created for snapshot 1. So it frees memory into non-existing mempool. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: fix register_snapshot deadlockMikulas Patocka2008-10-30
| | | | | | | | | | | | | | | register_snapshot() performs a GFP_KERNEL allocation while holding _origins_lock for write, but that could write out dirty pages onto a device that attempts to acquire _origins_lock for read, resulting in deadlock. So move the allocation up before taking the lock. This path is not performance-critical, so it doesn't matter that we allocate memory and free it if we find that we won't need it. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: drop unused last_percentMikulas Patocka2008-10-21
| | | | | | | | The last_percent field is unused - remove it. (It dates from when events were triggered as each X% filled up.) Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: fix primary_pe raceMikulas Patocka2008-10-21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix a race condition with primary_pe ref_count handling. put_pending_exception runs under dm_snapshot->lock, it does atomic_dec_and_test on primary_pe->ref_count, and later does atomic_read primary_pe->ref_count. __origin_write does atomic_dec_and_test on primary_pe->ref_count without holding dm_snapshot->lock. This opens the following race condition: Assume two CPUs, CPU1 is executing put_pending_exception (and holding dm_snapshot->lock). CPU2 is executing __origin_write in parallel. primary_pe->ref_count == 2. CPU1: if (primary_pe && atomic_dec_and_test(&primary_pe->ref_count)) origin_bios = bio_list_get(&primary_pe->origin_bios); ... decrements primary_pe->ref_count to 1. Doesn't load origin_bios CPU2: if (first && atomic_dec_and_test(&primary_pe->ref_count)) { flush_bios(bio_list_get(&primary_pe->origin_bios)); free_pending_exception(primary_pe); /* If we got here, pe_queue is necessarily empty. */ return r; } ... decrements primary_pe->ref_count to 0, submits pending bios, frees primary_pe. CPU1: if (!primary_pe || primary_pe != pe) free_pending_exception(pe); ... this has no effect. if (primary_pe && !atomic_read(&primary_pe->ref_count)) free_pending_exception(primary_pe); ... sees ref_count == 0 (written by CPU 2), does double free !! This bug can happen only if someone is simultaneously writing to both the origin and the snapshot. If someone is writing only to the origin, __origin_write will submit kcopyd request after it decrements primary_pe->ref_count (so it can't happen that the finished copy races with primary_pe->ref_count decrementation). If someone is writing only to the snapshot, __origin_write isn't invoked at all and the race can't happen. The race happens when someone writes to the snapshot --- this creates pending_exception with primary_pe == NULL and starts copying. Then, someone writes to the same chunk in the snapshot, and __origin_write races with termination of already submitted request in pending_complete (that calls put_pending_exception). This race may be reason for bugs: http://bugzilla.kernel.org/show_bug.cgi?id=11636 https://bugzilla.redhat.com/show_bug.cgi?id=465825 The patch fixes the code to make sure that: 1. If atomic_dec_and_test(&primary_pe->ref_count) returns false, the process must no longer dereference primary_pe (because someone else may free it under us). 2. If atomic_dec_and_test(&primary_pe->ref_count) returns true, the process is responsible for freeing primary_pe. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Cc: stable@kernel.org
* dm snapshot: use per device mempoolsMikulas Patocka2008-07-21
| | | | | | | | | | Change snapshot per-module mempool to per-device mempool. Per-module mempools could cause a deadlock if multiple snapshot devices are stacked above each other. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: fix race during exception creationMikulas Patocka2008-07-21
| | | | | | | | | | | | | | | | | | | | | Fix a race condition that returns incorrect data when a write causes an exception to be allocated whilst a read is still in flight. The race condition happens as follows: * A read to non-reallocated sector in the snapshot is submitted so that the read is routed to the original device. * A write to the original device is submitted. The write causes an exception that reallocates the block. The write proceeds. * The original read is dequeued and reads the wrong data. This race can be triggered with CFQ scheduler and one thread writing and multiple threads reading simultaneously. (This patch relies upon the earlier dm-kcopyd-per-device.patch to avoid a deadlock.) Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: track snapshot readsMikulas Patocka2008-07-21
| | | | | | | | | | | | Whenever a snapshot read gets mapped through to the origin, track it in a per-snapshot hash table indexed by chunk number, using memory allocated from a new per-snapshot mempool. We need to track these reads to avoid race conditions which will be fixed by patches that follow. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: move include filesAlasdair G Kergon2008-04-25
| | | | | | Publish the dm-io, dm-log and dm-kcopyd headers in include/linux. Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm kcopyd: clean interfaceHeinz Mauelshagen2008-04-25
| | | | | | | Clean up the kcopyd interface to prepare for publishing it in include/linux. Signed-off-by: Heinz Mauelshagen <hjm@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm io: clean interfaceHeinz Mauelshagen2008-04-25
| | | | | | | Clean up the dm-io interface to prepare for publishing it in include/linux. Signed-off-by: Heinz Mauelshagen <hjm@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: store pointer to target instanceMikulas Patocka2008-04-25
| | | | | | | Save pointer to dm_target in dm_snapshot structure. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: reduce default memory allocationMilan Broz2008-04-25
| | | | | | | | | Limit the amount of memory allocated per snapshot on systems with a large page size. (The larger default chunk size on these systems compensates for the smaller number of pages reserved.) Signed-off-by: Milan Broz <mbroz@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm io: write error bits form long not intAlasdair G Kergon2008-03-28
| | | | | | | | | | | | write_err is an unsigned long used with set_bit() so should not be passed around as unsigned int. http://bugzilla.kernel.org/show_bug.cgi?id=10271 Signed-off-by: Alasdair G Kergon <agk@redhat.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* dm snapshot: combine consecutive exceptions in memoryMilan Broz2008-02-07
| | | | | | | | | Provided sector_t is 64 bits, reduce the in-memory footprint of the snapshot exception table by the simple method of using unused bits of the chunk number to combine consecutive entries. Signed-off-by: Milan Broz <mbroz@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm snapshot: use rounddown_pow_of_twoRobert P. J. Day2008-02-07
| | | | | | | | Since the source file already includes the log2.h header file, it seems pointless to re-invent the necessary routine. Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* dm: use is_power_of_2vignesh babu2007-10-19
| | | | | | | Replacing n & (n - 1) for power of 2 check by is_power_of_2(n) Signed-off-by: vignesh babu <vignesh.babu@wipro.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
* Drop 'size' argument from bio_endio and bi_end_ioNeilBrown2007-10-10
| | | | | | | | | | | | | As bi_end_io is only called once when the reqeust is complete, the 'size' argument is now redundant. Remove it. Now there is no need for bio_endio to subtract the size completed from bi_size. So don't do that either. While we are at it, change bi_end_io to return void. Signed-off-by: Neil Brown <neilb@suse.de> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* dm: disable barriersStefan Bader2007-07-12
| | | | | | | | | | | | | This patch causes device-mapper to reject any barrier requests. This is done since most of the targets won't handle this correctly anyway. So until the situation improves it is better to reject these requests at the first place. Since barrier requests won't get to the targets, the checks there can be removed. Cc: stable@kernel.org Signed-off-by: Stefan Bader <shbader@de.ibm.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* dm snapshot: permit invalid activationMilan Broz2007-07-12
| | | | | | | | | | | | | Allow invalid snapshots to be activated instead of failing. This allows userspace to reinstate any given snapshot state - for example after an unscheduled reboot - and clean up the invalid snapshot at its leisure. Cc: stable@kernel.org Signed-off-by: Milan Broz <mbroz@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* dm: use kmem_cache macroAlasdair G Kergon2007-07-12
| | | | | | | | | | Use new KMEM_CACHE() macro and make the newly-exposed structure names more meaningful. Also remove some superfluous casts and inlines (let a modern compiler be the judge). Acked-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] make drivers/md/dm-snap.c:ksnapd staticAdrian Bunk2006-12-08
| | | | | | | Signed-off-by: Adrian Bunk <bunk@stusta.de> Acked-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dm: snapshot: abstract memory releaseMilan Broz2006-12-08
| | | | | | | | | | Move the code that releases memory used by a snapshot into a separate function. Signed-off-by: Milan Broz <mbroz@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Cc: dm-devel@redhat.com Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dm: map and endio symbolic return codesKiyoshi Ueda2006-12-08
| | | | | | | | | | | | | | | | | Update existing targets to use the new symbols for return values from target map and end_io functions. There is no effect on behaviour. Test results: Done build test without errors. Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Cc: dm-devel@redhat.com Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] slab: remove kmem_cache_tChristoph Lameter2006-12-07
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Replace all uses of kmem_cache_t with struct kmem_cache. The patch was generated using the following script: #!/bin/sh # # Replace one string by another in all the kernel sources. # set -e for file in `find * -name "*.c" -o -name "*.h"|xargs grep -l $1`; do quilt add $file sed -e "1,\$s/$1/$2/g" $file >/tmp/$$ mv /tmp/$$ $file quilt refresh done The script was run like this sh replace kmem_cache_t "struct kmem_cache" Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* WorkStruct: make allyesconfigDavid Howells2006-11-22
| | | | | | Fix up for make allyesconfig. Signed-Off-By: David Howells <dhowells@redhat.com>
* [PATCH] dm snapshot: fix freeing pending exceptionAlasdair G Kergon2006-10-03
| | | | | | | | | | | | | | If a snapshot became invalid while there are outstanding pending_exceptions, when pending_complete() processes each one it forgets to remove the corresponding exception from its exception table before freeing it. Fix this by moving the 'out:' label up one statement so that remove_exception() is always called. Then __invalidate_exception() no longer needs to call it and its 'pe' argument become superfluous. Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dm snapshot: tidy pe ref countingAlasdair G Kergon2006-10-03
| | | | | | | | Rename sibling_count to ref_count and introduce get and put functions. Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dm snapshot: add workqueueAlasdair G Kergon2006-10-03
| | | | | | | | | | | | Add a workqueue so that I/O can be queued up to be flushed from a separate thread (e.g. if local interrupts are disabled). A new per-snapshot spinlock pe_lock is introduced to protect queued_bios. Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dm snapshot: tidy pending_completeAlasdair G Kergon2006-10-03
| | | | | | | | | | | | | This patch rearranges the pending_complete() code so that the functional changes in subsequent patches are clearer. By consolidating the error and the non-error paths, we can move error_snapshot_bios() and __flush_bios() in line. Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dm snapshot: tidy snapshot_mapAlasdair G Kergon2006-10-03
| | | | | | | | | | | | This patch rearranges the snapshot_map code so that the functional changes in subsequent patches are clearer. The only functional change is to replace the existing read lock with a write lock which the next patch needs. Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dm snapshot: fix metadata error handlingMark McLoughlin2006-10-03
| | | | | | | | | | Fix the error handling when store.read_metadata is called: the error should be returned immediately. Signed-off-by: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dm snapshot: allow zero chunk_sizeMark McLoughlin2006-10-03
| | | | | | | | | | | | The chunk size of snapshots cannot be changed so it is redundant to require it as a parameter when activating an existing snapshot. Allow a value of zero in this case and ignore it. For a new snapshot, use a default value if zero is specified. Signed-off-by: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dm snapshot: fix invalidation ENOMEMMilan Broz2006-10-03
| | | | | | | | | Fix ENOMEM error sign. Signed-off-by: Milan Broz <mbroz@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* Remove obsolete #include <linux/config.h>Jörn Engel2006-06-30
| | | | | Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de> Signed-off-by: Adrian Bunk <bunk@stusta.de>
* [PATCH] dm: improve error message consistencyAlasdair G Kergon2006-06-26
| | | | | | | | | Tidy device-mapper error messages to include context information automatically. Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dm snapshot: unify chunk_sizeAlasdair G Kergon2006-06-26
| | | | | | | | | | | | | | | | | | | | | | | Persistent snapshots currently store a private copy of the chunk size. Userspace also supplies the chunk size when loading a snapshot. Ensure consistency by only storing the chunk_size in one place instead of two. Currently the two sizes will differ if the chunk size supplied by userspace does not match the chunk size an existing snapshot actually uses. Amongst other problems, this causes an incorrect 'percentage full' to be reported. The patch ensures consistency by only storing the chunk_size in one place, removing it from struct pstore. Some initialisation is delayed until the correct chunk_size is known. If read_header() discovers that the wrong chunk size was supplied, the 'area' buffer (which the header already got read into) is reinitialised to the correct size. [akpm: too late for 2.6.17 - suitable for 2.6.17.x after it has settled] Signed-off-by: Alasdair G Kergon <agk@redhat.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dm snapshot: fix kcopyd destructorAlasdair G Kergon2006-03-27
| | | | | | | | | | | | | | | | | | Before removing a snapshot, wait for the completion of any kcopyd jobs using it. Do this by maintaining a count (nr_jobs) of how many outstanding jobs each kcopyd_client has. The snapshot destructor first unregisters the snapshot so that no new kcopyd jobs (created by writes to the origin) will reference that particular snapshot. kcopyd_client_destroy() is now run next to wait for the completion of any outstanding jobs before the snapshot exception structures (that those jobs reference) are freed. Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] dm: remove SECTOR_FORMATAndrew Morton2006-03-27
| | | | | | | | | | | | | We don't know what type sector_t has. Sometimes it's unsigned long, sometimes it's unsigned long long. For example on ppc64 it's unsigned long with CONFIG_LBD=n and on x86_64 it's unsigned long long with CONFIG_LBD=n. The way to handle all of this is to always use unsigned long long and to always typecast the sector_t when printing it. Acked-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] device-mapper snapshot: fix invalidationAlasdair G Kergon2006-03-27
| | | | | | | | | | | | | | | | | When a snapshot becomes invalid, s->valid is set to 0. In this state, a snapshot can no longer be accessed. When s->lock is acquired, before doing anything else, s->valid must be checked to ensure the snapshot remains valid. This patch eliminates some races (that may cause panics) by adding some missing checks. At the same time, some unnecessary levels of indentation are removed and snapshot invalidation is moved into a single function that always generates a device-mapper event. Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] device-mapper snapshot: replace sibling listAlasdair G Kergon2006-03-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The siblings "list" is used unsafely at the moment. Firstly, only the element on the list being changed gets locked (via the snapshot lock), not the next and previous elements which have pointers that are also being changed. Secondly, if you have two or more snapshots and write to the same chunk a second time before every snapshot has finished making its private copy of the data, if you're unlucky, _origin_write() could attempt its list_merge() and dereference a 'last' pointer to a pending_exception structure that has just been freed. Analysis reveals that the list is actually only there for reference counting. If 5 pending_exceptions are needed in origin_write, then the 5 are joined together into a 5-element list - without a separate list head because there's nowhere suitable to store it. As the pending_exceptions complete, they are removed from the list one-by-one and any contents of origin_bios get moved across to one of the remaining pending_exceptions on the list. Whichever one is last is detected because list_empty() is then true and the origin_bios get submitted. The fix proposed here uses an alternative reference counting mechanism by choosing one of the pending_exceptions as primary and maintaining an atomic counter there. Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] device-mapper snapshot: fix origin_write pending_exception submissionAlasdair G Kergon2006-03-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Say you have several snapshots of the same origin and then you issue a write to some place in the origin for the first time. Before the device-mapper snapshot target lets the write go through to the underlying device, it needs to make a copy of the data that is about to be overwritten. Each snapshot is independent, so it makes one copy for each snapshot. __origin_write() loops through each snapshot and checks to see whether a copy is needed for that snapshot. (A copy is only needed the first time that data changes.) If a copy is needed, the code allocates a 'pending_exception' structure holding the details. It links these together for all the snapshots, then works its way through this list and submits the copying requests to the kcopyd thread by calling start_copy(). When each request is completed, the original pending_exception structure gets freed in pending_complete(). If you're very unlucky, this structure can get freed *before* the submission process has finished walking the list. This patch: 1) Creates a new temporary list pe_queue to hold the pending exception structures; 2) Does all the bookkeeping up-front, then walks through the new list safely and calls start_copy() for each pending_exception that needed it; 3) Avoids attempting to add pe->siblings to the list if it's already connected. [NB This does not fix all the races in this code. More patches will follow.] Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mempool: use mempool_create_slab_pool()Matthew Dobson2006-03-26
| | | | | | | | | | Modify well over a dozen mempool users to call mempool_create_slab_pool() rather than calling mempool_create() with extra arguments, saving about 30 lines of code and increasing readability. Signed-off-by: Matthew Dobson <colpatch@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] device-mapper snapshot: barriers not supportedAlasdair G Kergon2006-02-01
| | | | | | | | | The snapshot and origin targets are incapable of handling barriers and need to indicate this. Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] device-mapper snapshot: load metadata on creationAlasdair G Kergon2006-02-01
| | | | | | | | | | | | | | Move snapshot metadata loading to happen when the table is created instead of when the device is resumed. Writes to the origin device don't trigger exceptions until each snapshot table becomes active when resume() is called on each snapshot. If you're using lvm2, for this patch to work properly you should update to lvm2 version 2.02.01 or later and device-mapper version 1.02.02 or later. Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Unlinline a bunch of other functionsArjan van de Ven2006-01-14
| | | | | | | | | | | Remove the "inline" keyword from a bunch of big functions in the kernel with the goal of shrinking it by 30kb to 40kb Signed-off-by: Arjan van de Ven <arjan@infradead.org> Signed-off-by: Ingo Molnar <mingo@elte.hu> Acked-by: Jeff Garzik <jgarzik@pobox.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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