The patch titled
md: avoid a possibility that a read error can wrongly propagate through md/raid1 to a filesystem.
has been added to the -mm tree. Its filename is
md-avoid-a-possibility-that-a-read-error-can-wrongly-propagate-through-md-raid1-to-a-filesystem.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: md: avoid a possibility that a read error can wrongly propagate through md/raid1 to a filesystem.
From: NeilBrown <neilb@xxxxxxx>
When a raid1 has only one working drive, we want read error to propagate up
to the filesystem as there is no point failing the last drive in an array.
Currently the code perform this check is racy. If a write and a read a
both submitted to a device on a 2-drive raid1, and the write fails followed
by the read failing, the read will see that there is only one working drive
and will pass the failure up, even though the one working drive is actually
the *other* one.
So, tighten up the locking.
Signed-off-by: Neil Brown <neilb@xxxxxxx>
Cc: <stable@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/md/raid1.c | 33 +++++++++++++++++++--------------
1 file changed, 19 insertions(+), 14 deletions(-)
diff -puN drivers/md/raid1.c~md-avoid-a-possibility-that-a-read-error-can-wrongly-propagate-through-md-raid1-to-a-filesystem drivers/md/raid1.c
--- a/drivers/md/raid1.c~md-avoid-a-possibility-that-a-read-error-can-wrongly-propagate-through-md-raid1-to-a-filesystem
+++ a/drivers/md/raid1.c
@@ -271,21 +271,25 @@ static int raid1_end_read_request(struct
*/
update_head_pos(mirror, r1_bio);
- if (uptodate || (conf->raid_disks - conf->mddev->degraded) <= 1) {
- /*
- * Set R1BIO_Uptodate in our master bio, so that
- * we will return a good error code for to the higher
- * levels even if IO on some other mirrored buffer fails.
- *
- * The 'master' represents the composite IO operation to
- * user-side. So if something waits for IO, then it will
- * wait for the 'master' bio.
+ if (uptodate)
+ set_bit(R1BIO_Uptodate, &r1_bio->state);
+ else {
+ /* If all other devices have failed, we want to return
+ * the error upwards rather than fail the last device.
+ * Here we redefine "uptodate" to mean "Don't want to retry"
*/
- if (uptodate)
- set_bit(R1BIO_Uptodate, &r1_bio->state);
+ unsigned long flags;
+ spin_lock_irqsave(&conf->device_lock, flags);
+ if (r1_bio->mddev->degraded == conf->raid_disks ||
+ (r1_bio->mddev->degraded == conf->raid_disks-1 &&
+ !test_bit(Faulty, &conf->mirrors[mirror].rdev->flags)))
+ uptodate = 1;
+ spin_unlock_irqrestore(&conf->device_lock, flags);
+ }
+ if (uptodate)
raid_end_bio_io(r1_bio);
- } else {
+ else {
/*
* oops, read error:
*/
@@ -992,13 +996,14 @@ static void error(mddev_t *mddev, mdk_rd
unsigned long flags;
spin_lock_irqsave(&conf->device_lock, flags);
mddev->degraded++;
+ set_bit(Faulty, &rdev->flags);
spin_unlock_irqrestore(&conf->device_lock, flags);
/*
* if recovery is running, make sure it aborts.
*/
set_bit(MD_RECOVERY_ERR, &mddev->recovery);
- }
- set_bit(Faulty, &rdev->flags);
+ } else
+ set_bit(Faulty, &rdev->flags);
set_bit(MD_CHANGE_DEVS, &mddev->flags);
printk(KERN_ALERT "raid1: Disk failure on %s, disabling device. \n"
" Operation continuing on %d devices\n",
_
Patches currently in -mm which might be from neilb@xxxxxxx are
origin.patch
revert-md-improve-partition-detection-in-md-array.patch
md-avoid-a-possibility-that-a-read-error-can-wrongly-propagate-through-md-raid1-to-a-filesystem.patch
nlmclnt_recovery-dont-use-clone_sighand.patch
git-md-accel.patch
freezer-add-try_to_freeze-calls-to-all-kernel-threads.patch
introduce-freezer-flags-rev-2.patch
use-menuconfig-objects-ii-md.patch
md-dm-reduce-stack-usage-with-stacked-block-devices.patch
-
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