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authorAndre Noll <maan@systemlinux.org>2009-02-06 15:10:52 +1100
committerNeilBrown <neilb@suse.de>2009-02-06 15:10:52 +1100
commit852c8bf484a0e17ee27f413ef26e87f522af5607 (patch)
treea2bf0b7c3a277c65cdad307a3d48ee358868769c
parent4706b349f4a8312d31b3d0cf61fe721699356920 (diff)
md: Fix a bug in linear.c causing which_dev() to return the wrong device.
ab5bd5cbc8d4b868378d062eed3d4240930fbb86 introduced the following bug in linear software raid for large arrays on 32 bit machines: which_dev() computes the device holding a given sector by shifting down the sector number to a 32 bit range, dividing by the array spacing and looking up the resulting index in the hash table of the array. Because the computed index might be slightly too small, a loop at the end of which_dev() increases the index until the given sector actually falls into the range of the device associated with that index. The changes of the above mentioned commit caused this loop to check whether the _index_ rather than the sector number is small enough, effectively bypassing the loop and thus possibly returning the wrong device. As reported by Simon Kirby, this leads to errors such as linear_make_request: Sector 2340486136 out of bounds on dev sdi: 156301312 sectors, offset 2109870464 Fix this bug by introducing a local variable for the index so that the variable containing the passed sector is left unchanged. Cc: stable@kernel.org Signed-off-by: Andre Noll <maan@systemlinux.org> Signed-off-by: NeilBrown <neilb@suse.de>
-rw-r--r--drivers/md/linear.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/md/linear.c b/drivers/md/linear.c
index 1e3aea9eecf1..09658b218474 100644
--- a/drivers/md/linear.c
+++ b/drivers/md/linear.c
@@ -25,13 +25,13 @@ static inline dev_info_t *which_dev(mddev_t *mddev, sector_t sector)
{
dev_info_t *hash;
linear_conf_t *conf = mddev_to_conf(mddev);
+ sector_t idx = sector >> conf->sector_shift;
/*
* sector_div(a,b) returns the remainer and sets a to a/b
*/
- sector >>= conf->sector_shift;
- (void)sector_div(sector, conf->spacing);
- hash = conf->hash_table[sector];
+ (void)sector_div(idx, conf->spacing);
+ hash = conf->hash_table[idx];
while (sector >= hash->num_sectors + hash->start_sector)
hash++;

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