From e4f3fabd67480bf2ad3f71aa6126ffb8bb7dc712 Mon Sep 17 00:00:00 2001 From: Bryan Gurney Date: Thu, 7 Mar 2019 15:42:39 -0500 Subject: dm: add dust target 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 Co-developed-by: Joe Shimkus Co-developed-by: John Dorminy Co-developed-by: John Pittman Co-developed-by: Thomas Jaskiewicz Signed-off-by: Mike Snitzer --- drivers/md/Kconfig | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'drivers/md/Kconfig') diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig index 2557f198e175..db269a348b20 100644 --- a/drivers/md/Kconfig +++ b/drivers/md/Kconfig @@ -436,6 +436,15 @@ config DM_DELAY If unsure, say N. +config DM_DUST + tristate "Bad sector simulation target" + depends on BLK_DEV_DM + ---help--- + A target that simulates bad sector behavior. + Useful for testing. + + If unsure, say N. + config DM_INIT bool "DM \"dm-mod.create=\" parameter support" depends on BLK_DEV_DM=y -- cgit