md: add documentation for bad block log

Previous patch in the bad block series added new sysfs interfaces
([unacknowledged_]bad_blocks) for each rdev without documentation.
Add it.

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
Namhyung Kim 2011-07-28 11:31:47 +10:00 committed by NeilBrown
parent 16c791a5af
commit 6e0d2d0312

View File

@ -419,7 +419,6 @@ Each directory contains:
written, it will be rejected.
recovery_start
When the device is not 'in_sync', this records the number of
sectors from the start of the device which are known to be
correct. This is normally zero, but during a recovery
@ -435,6 +434,20 @@ Each directory contains:
Setting this to 'none' is equivalent to setting 'in_sync'.
Setting to any other value also clears the 'in_sync' flag.
bad_blocks
This gives the list of all known bad blocks in the form of
start address and length (in sectors respectively). If output
is too big to fit in a page, it will be truncated. Writing
"sector length" to this file adds new acknowledged (i.e.
recorded to disk safely) bad blocks.
unacknowledged_bad_blocks
This gives the list of known-but-not-yet-saved-to-disk bad
blocks in the same form of 'bad_blocks'. If output is too big
to fit in a page, it will be truncated. Writing to this file
adds bad blocks without acknowledging them. This is largely
for testing.
An active md device will also contain and entry for each active device