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path: root/drivers/md/raid10.c
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2012-11-22md/raid10: close race that lose writes lost when replacement completes.NeilBrown
When a replacement operation completes there is a small window when the original device is marked 'faulty' and the replacement still looks like a replacement. The faulty should be removed and the replacement moved in place very quickly, bit it isn't instant. So the code write out to the array must handle the possibility that the only working device for some slot in the replacement - but it doesn't. If the primary device is faulty it just gives up. This can lead to corruption. So make the code more robust: if either the primary or the replacement is present and working, write to them. Only when neither are present do we give up. This bug has been present since replacement was introduced in 3.3, so it is suitable for any -stable kernel since then. Reported-by: "George Spelvin" <linux@horizon.com> Cc: stable@vger.kernel.org Signed-off-by: NeilBrown <neilb@suse.de>
2012-10-31MD RAID10: Fix oops when creating RAID10 arrays via dm-raid.cJonathan Brassow
Commit 2863b9eb didn't take into account the changes to add TRIM support to RAID10 (commit 532a2a3fb). That is, when using dm-raid.c to create the RAID10 arrays, there is no mddev->gendisk or mddev->queue. The code added to support TRIM simply assumes that mddev->queue is available without checking. The result is an oops any time dm-raid.c attempts to create a RAID10 device. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: NeilBrown <neilb@suse.de>
2012-10-13Merge tag 'md-3.7' of git://neil.brown.name/mdLinus Torvalds
Pull md updates from NeilBrown: - "discard" support, some dm-raid improvements and other assorted bits and pieces. * tag 'md-3.7' of git://neil.brown.name/md: (29 commits) md: refine reporting of resync/reshape delays. md/raid5: be careful not to resize_stripes too big. md: make sure manual changes to recovery checkpoint are saved. md/raid10: use correct limit variable md: writing to sync_action should clear the read-auto state. Subject: [PATCH] md:change resync_mismatches to atomic64_t to avoid races md/raid5: make sure to_read and to_write never go negative. md: When RAID5 is dirty, force reconstruct-write instead of read-modify-write. md/raid5: protect debug message against NULL derefernce. md/raid5: add some missing locking in handle_failed_stripe. MD: raid5 avoid unnecessary zero page for trim MD: raid5 trim support md/bitmap:Don't use IS_ERR to judge alloc_page(). md/raid1: Don't release reference to device while handling read error. raid: replace list_for_each_continue_rcu with new interface add further __init annotations to crypto/xor.c DM RAID: Fix for "sync" directive ineffectiveness DM RAID: Fix comparison of index and quantity for "rebuild" parameter DM RAID: Add rebuild capability for RAID10 DM RAID: Move 'rebuild' checking code to its own function ...
2012-10-11md/raid10: use correct limit variableDan Carpenter
Clang complains that we are assigning a variable to itself. This should be using bad_sectors like the similar earlier check does. Bug has been present since 3.1-rc1. It is minor but could conceivably cause corruption or other bad behaviour. Cc: stable@vger.kernel.org Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: NeilBrown <neilb@suse.de>
2012-10-11Subject: [PATCH] md:change resync_mismatches to atomic64_t to avoid racesJianpeng Ma
Now that multiple threads can handle stripes, it is safer to use an atomic64_t for resync_mismatches, to avoid update races. Signed-off-by: Jianpeng Ma <majianpeng@gmail.com> Signed-off-by: NeilBrown <neilb@suse.de>
2012-10-11MD RAID10: Prep for DM RAID10 device replacement capabilityJonathan Brassow
MD RAID10: Fix a couple potential kernel panics if RAID10 is used by dm-raid When device-mapper uses the RAID10 personality through dm-raid.c, there is no 'gendisk' structure in mddev and some sysfs information is also not populated. This patch avoids touching those non-existent structures. Signed-off-by: Jonathan Brassow <jbrassow@rehdat.com> Signed-off-by: NeilBrown <neilb@suse.de>
2012-10-11MD: change the parameter of md threadShaohua Li
Change the thread parameter, so the thread can carry extra info. Next patch will use it. Signed-off-by: Shaohua Li <shli@fusionio.com> Signed-off-by: NeilBrown <neilb@suse.de>
2012-10-11md/raid10: submit IO from originating thread instead of md thread.NeilBrown
queuing writes to the md thread means that all requests go through the one processor which may not be able to keep up with very high request rates. So use the plugging infrastructure to submit all requests on unplug. If a 'schedule' is needed, we fall back on the old approach of handing the requests to the thread for it to handle. This is nearly identical to a recent patch which provided similar functionality to RAID1. Signed-off-by: NeilBrown <neilb@suse.de>
2012-10-11md: raid 10 supports TRIMShaohua Li
This makes md raid 10 support TRIM. If one disk supports discard and another not, or one has discard_zero_data and another not, there could be inconsistent between data from such disks. But this should not matter, discarded data is useless. This will add extra copy in rebuild though. Signed-off-by: Shaohua Li <shli@fusionio.com> Signed-off-by: NeilBrown <neilb@suse.de>
2012-09-27md/raid10: fix "enough" function for detecting if array is failed.NeilBrown
The 'enough' function is written to work with 'near' arrays only in that is implicitly assumes that the offset from one 'group' of devices to the next is the same as the number of copies. In reality it is the number of 'near' copies. So change it to make this number explicit. This bug makes it possible to run arrays without enough drives present, which is dangerous. It is appropriate for an -stable kernel, but will almost certainly need to be modified for some of them. Cc: stable@vger.kernel.org Reported-by: Jakub Husák <jakub@gooseman.cz> Signed-off-by: NeilBrown <neilb@suse.de>
2012-08-18md/raid10: fix problem with on-stack allocation of r10bio structure.NeilBrown
A 'struct r10bio' has an array of per-copy information at the end. This array is declared with size [0] and r10bio_pool_alloc allocates enough extra space to store the per-copy information depending on the number of copies needed. So declaring a 'struct r10bio on the stack isn't going to work. It won't allocate enough space, and memory corruption will ensue. So in the two places where this is done, declare a sufficiently large structure and use that instead. The two call-sites of this bug were introduced in 3.4 and 3.5 so this is suitable for both those kernels. The patch will have to be modified for 3.4 as it only has one bug. Cc: stable@vger.kernel.org Reported-by: Ivan Vasilyev <ivan.vasilyev@gmail.com> Tested-by: Ivan Vasilyev <ivan.vasilyev@gmail.com> Signed-off-by: NeilBrown <neilb@suse.de>
2012-08-01Merge branch 'for-3.6/drivers' of git://git.kernel.dk/linux-blockLinus Torvalds
Pull block driver changes from Jens Axboe: - Making the plugging support for drivers a bit more sane from Neil. This supersedes the plugging change from Shaohua as well. - The usual round of drbd updates. - Using a tail add instead of a head add in the request completion for ndb, making us find the most completed request more quickly. - A few floppy changes, getting rid of a duplicated flag and also running the floppy init async (since it takes forever in boot terms) from Andi. * 'for-3.6/drivers' of git://git.kernel.dk/linux-block: floppy: remove duplicated flag FD_RAW_NEED_DISK blk: pass from_schedule to non-request unplug functions. block: stack unplug blk: centralize non-request unplug handling. md: remove plug_cnt feature of plugging. block/nbd: micro-optimization in nbd request completion drbd: announce FLUSH/FUA capability to upper layers drbd: fix max_bio_size to be unsigned drbd: flush drbd work queue before invalidate/invalidate remote drbd: fix potential access after free drbd: call local-io-error handler early drbd: do not reset rs_pending_cnt too early drbd: reset congestion information before reporting it in /proc/drbd drbd: report congestion if we are waiting for some userland callback drbd: differentiate between normal and forced detach drbd: cleanup, remove two unused global flags floppy: Run floppy initialization asynchronous
2012-07-31md: remove plug_cnt feature of plugging.NeilBrown
This seemed like a good idea at the time, but after further thought I cannot see it making a difference other than very occasionally and testing to try to exercise the case it is most likely to help did not show any performance difference by removing it. So remove the counting of active plugs and allow 'pending writes' to be activated at any time, not just when no plugs are active. This is only relevant when there is a write-intent bitmap, and the updating of the bitmap will likely introduce enough delay that the single-threading of bitmap updates will be enough to collect large numbers of updates together. Removing this will make it easier to centralise the unplug code, and will clear the other for other unplug enhancements which have a measurable effect. Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-07-31MD RAID10: Export md_raid10_congestedJonathan Brassow
md/raid10: Export is_congested test. In similar fashion to commits 11d8a6e3719519fbc0e2c9d61b6fa931b84bf813 1ed7242e591af7e233234d483f12d33818b189d9 we export the RAID10 congestion checking function so that dm-raid.c can make use of it and make use of the personality. The 'queue' and 'gendisk' structures will not be available to the MD code when device-mapper sets up the device, so we conditionalize access to these fields also. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: NeilBrown <neilb@suse.de>
2012-07-31MD: Move macros from raid1*.h to raid1*.cJonathan Brassow
MD RAID1/RAID10: Move some macros from .h file to .c file There are three macros (IO_BLOCKED,IO_MADE_GOOD,BIO_SPECIAL) which are defined in both raid1.h and raid10.h. They are only used in there respective .c files. However, if we wish to make RAID10 accessible to the device-mapper RAID target (dm-raid.c), then we need to move these macros into the .c files where they are used so that they do not conflict with each other. The macros from the two files are identical and could be moved into md.h, but I chose to leave the duplication and have them remain in the personality files. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: NeilBrown <neilb@suse.de>
2012-07-31MD RAID10: rename mirror_info structureJonathan Brassow
MD RAID10: Rename the structure 'mirror_info' to 'raid10_info' The same structure name ('mirror_info') is used by raid1. Each of these structures are defined in there respective header files. If dm-raid is to support both RAID1 and RAID10, the header files will be included and the structure names must not collide. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: NeilBrown <neilb@suse.de>
2012-07-31MD RAID10: Fix compiler warning.Jonathan Brassow
MD RAID10: Fix compiler warning. Initialize variable to prevent compiler warning. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: NeilBrown <neilb@suse.de>
2012-07-04md/raid10: fix careless build errorNeilBrown
build error introduced by commit b357f04a67c2aeee8 That function doesn't get extra args until a later patch. Bother. Reported-by: Fengguang Wu <wfg@linux.intel.com> Reported-by: Simon Kirby <sim@hostway.ca> Reported-by: Tobias Klausmann <tobias.johannes.klausmann@mni.thm.de> Signed-off-by: NeilBrown <neilb@suse.de>
2012-07-03md: fix up plugging (again).NeilBrown
The value returned by "mddev_check_plug" is only valid until the next 'schedule' as that will unplug things. This could happen at any call to mempool_alloc. So just calling mddev_check_plug at the start doesn't really make sense. So call it just before, or just after, queuing things for the thread. As the action that happens at unplug is to wake the thread, this makes lots of sense. If we cannot add a plug (which requires a small GFP_ATOMIC alloc) we wake thread immediately. RAID5 is a bit different. Requests are queued for the thread and the thread is woken by release_stripe. So we don't need to wake the thread on failure. However the thread doesn't perform certain actions when there is any active plug, so it is important to install a plug before waking the thread. So for RAID5 we install the plug *before* queuing the request and waking the thread. Without this patch it is possible for raid1 or raid10 to queue a request without then waking the thread, resulting in the array locking up. Also change raid10 to only flush_pending_write when there are not active plugs, just like raid1. This patch is suitable for 3.0 or later. I plan to submit it to -stable, but I'll like to let it spend a few weeks in mainline first to be sure it is completely safe. Signed-off-by: NeilBrown <neilb@suse.de>
2012-07-03md: make 'name' arg to md_register_thread non-optional.NeilBrown
Having the 'name' arg optional and defaulting to the current personality name is no necessary and leads to errors, as when changing the level of an array we can end up using the name of the old level instead of the new one. So make it non-optional and always explicitly pass the name of the level that the array will be. Reported-by: majianpeng <majianpeng@gmail.com> Signed-off-by: NeilBrown <neilb@suse.de>
2012-07-03md/raid10: fix failure when trying to repair a read error.NeilBrown
commit 58c54fcca3bac5bf9290cfed31c76e4c4bfbabaf md/raid10: handle further errors during fix_read_error better. in 3.1 added "r10_sync_page_io" which takes an IO size in sectors. But we were passing the IO size in bytes!!! This resulting in bio_add_page failing, and empty request being sent down, and a consequent BUG_ON in scsi_lib. [fix missing space in error message at same time] This fix is suitable for 3.1.y and later. Cc: stable@vger.kernel.org Reported-by: Christian Balzer <chibi@gol.com> Signed-off-by: NeilBrown <neilb@suse.de>
2012-07-03md/raid10: Don't try to recovery unmatched (and unused) chunks.NeilBrown
If a RAID10 has an odd number of chunks - as might happen when there are an odd number of devices - the last chunk has no pair and so is not mirrored. We don't store data there, but when recovering the last device in an array we retry to recover that last chunk from a non-existent location. This results in an error, and the recovery aborts. When we get to that last chunk we should just stop - there is nothing more to do anyway. This bug has been present since the introduction of RAID10, so the patch is appropriate for any -stable kernel. Cc: stable@vger.kernel.org Reported-by: Christian Balzer <chibi@gol.com> Tested-by: Christian Balzer <chibi@gol.com> Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-31md: raid1/raid10: fix problem with merge_bvec_fnNeilBrown
The new merge_bvec_fn which calls the corresponding function in subsidiary devices requires that mddev->merge_check_needed be set if any child has a merge_bvec_fn. However were were only setting that when a device was hot-added, not when a device was present from the start. This bug was introduced in 3.4 so patch is suitable for 3.4.y kernels. However that are conflicts in raid10.c so a separate patch will be needed for 3.4.y. Cc: stable@vger.kernel.org Reported-by: Sebastian Riemer <sebastian.riemer@profitbricks.com> Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22md/raid10: Remove extras after reshape to smaller number of devices.NeilBrown
When a reshape which reduced the number of devices finishes we must remove the extra devices. So ensure that raid10_remove_disk won't try to keep them, and have raid10_finish_reshape clear the 'in_sync' flag. Then remove_and_add_spares will be able to remove them. Reported-by: Hannes Reinecke <hare@suse.com> Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22md/raid10: resize bitmap when required during reshape.NeilBrown
If a reshape changes the size of the array, then we can now update the bitmap to suit - so do so. Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22md: allow array to be resized while bitmap is present.NeilBrown
Now that bitmaps can be resized, we can allow an array to be resized while the bitmap is present. This only covers resizing that involves changing the effective size of member devices, not resizing that changes the number of devices. Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22md/raid10: Fix memleak in r10buf_pool_allocmajianpeng
If the allocation of rep1_bio fails, we currently don't free the 'bio' of the same dev. Reported by kmemleak. Signed-off-by: majianpeng <majianpeng@gmail.com> Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-22md/raid10: add reshape supportNeilBrown
A 'near' or 'offset' lay RAID10 array can be reshaped to a different 'near' or 'offset' layout, a different chunk size, and a different number of devices. However the number of copies cannot change. Unlike RAID5/6, we do not support having user-space backup data that is being relocated during a 'critical section'. Rather, the data_offset of each device must change so that when writing any block to a new location, it will not over-write any data that is still 'live'. This means that RAID10 reshape is not supportable on v0.90 metadata. The different between the old data_offset and the new_offset must be at least the larger of the chunksize multiplied by offset copies of each of the old and new layout. (for 'near' mode, offset_copies == 1). A larger difference of around 64M seems useful for in-place reshapes as more data can be moved between metadata updates. Very large differences (e.g. 512M) seem to slow the process down due to lots of long seeks (on oldish consumer graded devices at least). Metadata needs to be updated whenever the place we are about to write to is considered - by the current metadata - to still contain data in the old layout. [unbalanced locking fix from Dan Carpenter <dan.carpenter@oracle.com>] Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-21md/raid10: split out interpretation of layout to separate function.NeilBrown
We will soon be interpreting the layout (and chunksize etc) from multiple places to support reshape. So split it out into separate function. Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-21md/raid10: Introduce 'prev' geometry to support reshape.NeilBrown
When RAID10 supports reshape it will need a 'previous' and a 'current' geometry, so introduce that here. Use the 'prev' geometry when before the reshape_position, and the current 'geo' when beyond it. At other times, use both as appropriate. For now, both are identical (And reshape_position is never set). When we use the 'prev' geometry, we must use the old data_offset. When we use the current (And a reshape is happening) we must use the new_data_offset. Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-21md/raid10: collect some geometry fields into a dedicated structure.NeilBrown
We will shortly be adding reshape support for RAID10 which will require it having 2 concurrent geometries (before and after). To make that easier, collect most geometry fields into 'struct geom' and access them from there. Then we will more easily be able to add a second set of fields. Note that 'copies' is not in this struct and so cannot be changed. There is little need to change this number and doing so is a lot more difficult as it requires reallocating more things. So leave it out for now. Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-21md: add possibility to change data-offset for devices.NeilBrown
When reshaping we can avoid costly intermediate backup by changing the 'start' address of the array on the device (if there is enough room). So as a first step, allow such a change to be requested through sysfs, and recorded in v1.x metadata. (As we didn't previous check that all 'pad' fields were zero, we need a new FEATURE flag for this. A (belatedly) check that all remaining 'pad' fields are zero to avoid a repeat of this) The new data offset must be requested separately for each device. This allows each to have a different change in the data offset. This is not likely to be used often but as data_offset can be set per-device, new_data_offset should be too. This patch also removes the 'acknowledged' arg to rdev_set_badblocks as it is never used and never will be. At the same time we add a new arg ('in_new') which is currently always zero but will be used more soon. When a reshape finishes we will need to update the data_offset and rdev->sectors. So provide an exported function to do that. Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-19md/raid10: fix transcription error in calc_sectors conversion.NeilBrown
The old code was sector_div(stride, fc); the new code was sector_dir(size, conf->near_copies); 'size' is right (the stride various wasn't really needed), but 'fc' means 'far_copies', and that is an important difference. Signed-off-by: NeilBrown <neilb@suse.de>
2012-05-17md/raid10: set dev_sectors properly when resizing devices in array.NeilBrown
raid10 stores dev_sectors in 'conf' separately from the one in 'mddev' because it can have a very significant effect on block addressing and so need to be updated carefully. However raid10_resize isn't updating it at all! To update it correctly, we need to make sure it is a proper multiple of the chunksize taking various details of the layout in to account. This calculation is currently done in setup_conf. So split it out from there and call it from raid10_resize as well. Then set conf->dev_sectors properly. Signed-off-by: NeilBrown <neilb@suse.de>
2012-04-12md/raid1,raid10: Fix calculation of 'vcnt' when processing error recovery.majianpeng
If r1bio->sectors % 8 != 0,then the memcmp and a later memcpy will omit the last bio_vec. This is suitable for any stable kernel since 3.1 when bad-block management was introduced. Cc: stable@vger.kernel.org Signed-off-by: majianpeng <majianpeng@gmail.com> Signed-off-by: NeilBrown <neilb@suse.de>
2012-04-03md/raid1,raid10: don't compare excess byte during consistency check.NeilBrown
When comparing two pages read from different legs of a mirror, only compare the bytes that were read, not the whole page. In most cases we read a whole page, but in some cases with bad blocks or odd sizes devices we might read fewer than that. This bug has been present "forever" but at worst it might cause a report of two many mismatches and generate a little bit extra resync IO, so there is no need to back-port to -stable kernels. Reported-by: majianpeng <majianpeng@gmail.com> Signed-off-by: NeilBrown <neilb@suse.de>
2012-03-19md/raid10 - support resizing some RAID10 arrays.NeilBrown
'resizing' an array in this context means making use of extra space that has become available in component devices, not adding new devices. It also includes shrinking the array to take up less space of component devices. This is not supported for array with a 'far' layout. However for 'near' and 'offset' layout arrays, adding and removing space at the end of the devices is easy to support, and this patch provides that support. Signed-off-by: NeilBrown <neilb@suse.de>
2012-03-19md/raid10: handle merge_bvec_fn in member devices.NeilBrown
Currently we don't honour merge_bvec_fn in member devices so if there is one, we force all requests to be single-page at most. This is not ideal. So enhance the raid10 merge_bvec_fn to check that function in children as well. This introduces a small problem. There is no locking around calls the ->merge_bvec_fn and subsequent calls to ->make_request. So a device added between these could end up getting a request which violates its merge_bvec_fn. Currently the best we can do is synchronize_sched(). This will work providing no preemption happens. If there is preemption, we just have to hope that new devices are largely consistent with old devices. Signed-off-by: NeilBrown <neilb@suse.de>
2012-03-19md: tidy up rdev_for_each usage.NeilBrown
md.h has an 'rdev_for_each()' macro for iterating the rdevs in an mddev. However it uses the 'safe' version of list_for_each_entry, and so requires the extra variable, but doesn't include 'safe' in the name, which is useful documentation. Consequently some places use this safe version without needing it, and many use an explicity list_for_each entry. So: - rename rdev_for_each to rdev_for_each_safe - create a new rdev_for_each which uses the plain list_for_each_entry, - use the 'safe' version only where needed, and convert all other list_for_each_entry calls to use rdev_for_each. Signed-off-by: NeilBrown <neilb@suse.de>
2012-03-19md/raid1,raid10: avoid deadlock during resync/recovery.NeilBrown
If RAID1 or RAID10 is used under LVM or some other stacking block device, it is possible to enter a deadlock during resync or recovery. This can happen if the upper level block device creates two requests to the RAID1 or RAID10. The first request gets processed, blocks recovery and queue requests for underlying requests in current->bio_list. A resync request then starts which will wait for those requests and block new IO. But then the second request to the RAID1/10 will be attempted and it cannot progress until the resync request completes, which cannot progress until the underlying device requests complete, which are on a queue behind that second request. So allow that second request to proceed even though there is a resync request about to start. This is suitable for any -stable kernel. Cc: stable@vger.kernel.org Reported-by: Ray Morris <support@bettercgi.com> Tested-by: Ray Morris <support@bettercgi.com> Signed-off-by: NeilBrown <neilb@suse.de>
2012-03-19md: allow re-add to failed arrays.NeilBrown
When an array is failed (some data inaccessible) then there is no point attempting to add a spare as it could not possibly be recovered. However that may be value in re-adding a recently removed device. e.g. if there is a write-intent-bitmap and it is clear, then access to the data could be restored by this action. So don't reject a re-add to a failed array for RAID10 and RAID5 (the only arrays types that check for a failed array). Signed-off-by: NeilBrown <neilb@suse.de>
2012-03-13md/raid10: remove unnecessary smp_mb() from end_sync_writeNeilBrown
Recent commit 4ca40c2ce099e4f1ce3 (md/raid10: Allow replacement device ...) added an smp_mb in end_sync_write. This was to close a possible race with raid10_remove_disk. However there is no such race as it is never attempted to remove a disk while resync (or recovery) is happening. so the smp_mb is just noise. Signed-off-by: NeilBrown <neilb@suse.de>
2012-03-06md/raid10: fix assembling of arrays with replacement devices.NeilBrown
commit 56a2559bb654a (md/raid10: recognise replacements ...) changed 'run' to set ->replacement or ->rdev depending on the 'Replacement' status if the device, but it didn't remove the old unconditional setting of 'rdev'. So it was largely ineffective. So remove that now. Signed-off-by: NeilBrown <neilb@suse.de>
2012-02-14md/raid10: fix handling of error on last working device in array.NeilBrown
If we get a read error on the last working device in a RAID10 which contains the target block, then we don't fail the device (which is good) but we don't abort retries, which is wrong. We end up in an infinite loop retrying the read on the one device. This patch fixes the problem in two places: 1/ in raid10_end_read_request we don't even ask for a retry if this was the last usable device. This is efficient but a little racy and will sometimes retry when it should not. 2/ in handle_read_error we are careful to exclude any device from retry which we tried to mark as faulty (that might have failed if it was the last device). This is race-free but less efficient. Signed-off-by: NeilBrown <neilb@suse.de>
2011-12-23md/raid10: If there is a spare and a want_replacement device, start replacement.NeilBrown
When attempting to add a spare to a RAID10 array, also consider adding it as a replacement for a want_replacement device. Signed-off-by: NeilBrown <neilb@suse.de>
2011-12-23md/raid10: recognise replacements when assembling array.NeilBrown
If a Replacement is seen, file it as such. If we see two replacements (or two normal devices) for the one slot, abort. Signed-off-by: NeilBrown <neilb@suse.de>
2011-12-23md/raid10: Allow replacement device to be replace old drive.NeilBrown
When recovery finish and spare_active is called, check for a replace that might have just become fully synced and mark it as such, marking the original as failed. Then when the original is removed, move the replacement into its position. This means that 'replacement' and spontaneously become NULL in some situations. Make sure we check for those. It also means that 'rdev' and 'replacement' could appear to be identical - check for that too. Signed-off-by: NeilBrown <neilb@suse.de>
2011-12-23md/raid10: handle recovery of replacement devices.NeilBrown
If there is a replacement device, then recover to it, reading from any drives - maybe the one being replaced, maybe not. Signed-off-by: NeilBrown <neilb@suse.de>
2011-12-23md/raid10: Handle replacement devices during resync.NeilBrown
If we need to resync an array which has replacement devices, we always write any block checked to every replacement. If the resync was bitmap-based resync we will then complete the replacement normally. If it was a full resync, we mark the replacements as fully recovered when the resync finishes so no further recovery is needed. Signed-off-by: NeilBrown <neilb@suse.de>
2011-12-23md/raid10: writes should get directed to replacement as well as original.NeilBrown
When writing, we need to submit two writes, one to the original, and one to the replacements - if there is a replacement. If the write to the replacement results in a write error we just fail the device. We only try to record write errors to the original. This only handles writing new data. Writing for resync/recovery will come later. Signed-off-by: NeilBrown <neilb@suse.de>