Add a limited write failure mode which allows a write to a block to fail
a specified amount of times, prior to remapping. The "addbadblock"
message is extended to allow specifying the limited number of times a
write fails.
Example: add bad block on block 60, with 5 write failures:
dmsetup message 0 dust1 addbadblock 60 5
The write failure counter will be printed for newly added bad blocks.
Signed-off-by: Bryan Gurney <bgurney@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
In the dust_map_read() and dust_map() functions, change the
return code variable "ret" to "r", to match the convention of the
other device-mapper targets.
Signed-off-by: Bryan Gurney <bgurney@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Change the "result" variables to "r" in dust_status() and
dust_message().
Signed-off-by: Bryan Gurney <bgurney@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Change the "frontend" dust_remove_block, dust_add_block, and
dust_query_block functions to store the "dust block number", instead
of the sector number corresponding to the "dust block number".
For the "backend" functions dust_map_read and dust_map_write,
right-shift by sect_per_block_shift. This fixes the inability to
emulate failure beyond the first sector of each "dust block" (for
devices with a "dust block size" larger than 512 bytes).
Fixes: e4f3fabd67 ("dm: add dust target")
Cc: stable@vger.kernel.org
Signed-off-by: Bryan Gurney <bgurney@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Fix sparse warnings:
drivers/md/dm-dust.c:495:12: warning: symbol 'dm_dust_init' was not declared. Should it be static?
drivers/md/dm-dust.c:505:13: warning: symbol 'dm_dust_exit' was not declared. Should it be static?
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Variable block is an unsigned long long hence the less than zero
comparison is always false, hence it is redundant and can be removed.
Addresses-Coverity: ("Unsigned compared against 0")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Bryan Gurney <bgurney@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Add the dm-dust target, which simulates the behavior of bad sectors
at arbitrary locations, and the ability to enable the emulation of
the read failures at an arbitrary time.
This target behaves similarly to a linear target. At a given time,
the user can send a message to the target to start failing read
requests on specific blocks. When the failure behavior is enabled,
reads of blocks configured "bad" will fail with EIO.
Writes of blocks configured "bad" will result in the following:
1. Remove the block from the "bad block list".
2. Successfully complete the write.
After this point, the block will successfully contain the written
data, and will service reads and writes normally. This emulates the
behavior of a "remapped sector" on a hard disk drive.
dm-dust provides logging of which blocks have been added or removed
to the "bad block list", as well as logging when a block has been
removed from the bad block list. These messages can be used
alongside the messages from the driver using a dm-dust device to
analyze the driver's behavior when a read fails at a given time.
(This logging can be reduced via a "quiet" mode, if desired.)
NOTE: If the block size is larger than 512 bytes, only the first sector
of each "dust block" is detected. Placing a limiting layer above a dust
target, to limit the minimum I/O size to the dust block size, will
ensure proper emulation of the given large block size.
Signed-off-by: Bryan Gurney <bgurney@redhat.com>
Co-developed-by: Joe Shimkus <jshimkus@redhat.com>
Co-developed-by: John Dorminy <jdorminy@redhat.com>
Co-developed-by: John Pittman <jpittman@redhat.com>
Co-developed-by: Thomas Jaskiewicz <tjaskiew@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
