kernel.git/drivers/md/raid10.c, branch linux-2.6.34.y

md/raid10: fix deadlock with unaligned read during resync

2010-08-13T20:27:20Z

commit 51e9ac77035a3dfcb6fc0a88a0d80b6f99b5edb1 upstream. If the 'bio_split' path in raid10-read is used while resync/recovery is happening it is possible to deadlock. Fix this be elevating ->nr_waiting for the duration of both parts of the split request. This fixes a bug that has been present since 2.6.22 but has only started manifesting recently for unknown reasons. It is suitable for and -stable since then. Reported-by: Justin Bronder Tested-by: Justin Bronder Signed-off-by: NeilBrown Signed-off-by: Greg Kroah-Hartman

md: raid10: Fix null pointer dereference in fix_read_error()

2010-08-02T17:29:42Z

commit 0544a21db02c1d8883158fd6f323364f830a120a upstream. Such NULL pointer dereference can occur when the driver was fixing the read errors/bad blocks and the disk was physically removed causing a system crash. This patch check if the rcu_dereference() returns valid rdev before accessing it in fix_read_error(). Signed-off-by: Prasanna S. Panchamukhi Signed-off-by: Rob Becker Signed-off-by: NeilBrown Signed-off-by: Greg Kroah-Hartman

md: Fix read balancing in RAID1 and RAID10 on drives > 2TB

2010-07-05T18:22:22Z

commit af3a2cd6b8a479345786e7fe5e199ad2f6240e56 upstream. read_balance uses a "unsigned long" for a sector number which will get truncated beyond 2TB. This will cause read-balancing to be non-optimal, and can cause data to be read from the 'wrong' branch during a resync. This has a very small chance of returning wrong data. Reported-by: Jordan Russell Signed-off-by: NeilBrown Signed-off-by: Greg Kroah-Hartman

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

2010-03-30T13:02:32Z

percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo Guess-its-ok-by: Christoph Lameter Cc: Ingo Molnar Cc: Lee Schermerhorn

md: deal with merge_bvec_fn in component devices better.

2010-03-16T06:04:24Z

If a component device has a merge_bvec_fn then as we never call it we must ensure we never need to. Currently this is done by setting max_sector to 1 PAGE, however this does not stop a bio being created with several sub-page iovecs that would violate the merge_bvec_fn. So instead set max_segments to 1 and set the segment boundary to the same as a page boundary to ensure there is only ever one single-page segment of IO requested at a time. This can particularly be an issue when 'xen' is used as it is known to submit multiple small buffers in a single bio. Signed-off-by: NeilBrown Cc: stable@kernel.org

block: Rename blk_queue_max_sectors to blk_queue_max_hw_sectors

2010-02-26T12:58:08Z

The block layer calling convention is blk_queue_. blk_queue_max_sectors predates this practice, leading to some confusion. Rename the function to appropriately reflect that its intended use is to set max_hw_sectors. Also introduce a temporary wrapper for backwards compability. This can be removed after the merge window is closed. Signed-off-by: Martin K. Petersen Signed-off-by: Jens Axboe

md: add MODULE_DESCRIPTION for all md related modules.

2009-12-14T01:51:41Z

Suggested by Oren Held Signed-off-by: NeilBrown

raid: improve MD/raid10 handling of correctable read errors.

2009-12-14T01:51:41Z

We've noticed severe lasting performance degradation of our raid arrays when we have drives that yield large amounts of media errors. The raid10 module will queue each failed read for retry, and also will attempt call fix_read_error() to perform the read recovery. Read recovery is performed while the array is frozen, so repeated recovery attempts can degrade the performance of the array for extended periods of time. With this patch I propose adding a per md device max number of corrected read attempts. Each rdev will maintain a count of read correction attempts in the rdev->read_errors field (not used currently for raid10). When we enter fix_read_error() we'll check to see when the last read error occurred, and divide the read error count by 2 for every hour since the last read error. If at that point our read error count exceeds the read error threshold, we'll fail the raid device. In addition in this patch I add sysfs nodes (get/set) for the per md max_read_errors attribute, the rdev->read_errors attribute, and added some printk's to indicate when fix_read_error fails to repair an rdev. For testing I used debugfs->fail_make_request to inject IO errors to the rdev while doing IO to the raid array. Signed-off-by: Robert Becker Signed-off-by: NeilBrown

md/raid10: print more useful messages on device failure.

2009-12-14T01:51:41Z

When we get a read error on a device in a RAID10, and attempting to repair the error fails, print more useful messages about why it failed. Signed-off-by: Robert Becker Signed-off-by: NeilBrown

md: remove needless setting of thread->timeout in raid10_quiesce

2009-12-14T01:51:41Z

As bitmap_create and bitmap_destroy already set thread->timeout as appropriate, there is no need to do it in raid10_quiesce. There is a possible need to wake the thread after the timeout has been set low, but it is better to do that where the timeout is actually set low, in bitmap_create. Signed-off-by: NeilBrown