This patch adds the device-mapper target dm-dust, which allows the arbitrary designation of "bad" sectors, at an arbitrary time. This target behaves similarly to a linear target, with the exception of the minimum and optimal IO sizes being configurable to 512 or 4096 bytes. 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". sector). 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.) Bryan Gurney (1): dm: add dust target Documentation/device-mapper/dm-dust.txt | 256 ++++++++++++ drivers/md/Kconfig | 9 + drivers/md/Makefile | 1 + drivers/md/dm-dust.c | 499 ++++++++++++++++++++++++ 4 files changed, 765 insertions(+) create mode 100644 Documentation/device-mapper/dm-dust.txt create mode 100644 drivers/md/dm-dust.c -- 2.17.2 -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
