dm flakey: document corrupt_bio_byte and optional feature precedence
Subsystems (2)
PATCH 1/1 dm flakey: document corrupt_bio_byte and optional feature precedence
Signed-off-by Mike Snitzer <[email protected]>
--- Documentation/device-mapper/dm-flakey.txt | 15 ++++++++++++++- 1 files changed, 14 insertions(+), 1 deletions(-)
Documentation/device-mapper/dm-flakey.txt +14 -1
@@ -27,7 +27,20 @@ Mandatory parameters: Optional feature parameters: If no feature parameters are present, during the periods of - unreliability, all I/O returns errors. + unreliability, all I/O returns errors. Optional features may be + combined (e.g. corrupt_bio_byte on READ and drop_writes). Conflicting + features (e.g. corrupt_bio_byte on WRITE and drop_writes) are resolved + according to the following feature precedence (descending order): + + corrupt_bio_byte <Nth byte> <bio_flags> <value>: + Corrupt bios that have specific bi_rw flag(s), e.g.: READ=0 or + REQ_WRITE=1|REQ_META=32, by writing <value> to the <Nth byte> of + bios that have data. + Examples: + 1) corrupt 32nd byte in READ bios with the value 1: + corrupt_bio_byte 32 0 1 + 2) corrupt 224th byte in WRITE|REQ_META bios with the value 0: + corrupt_bio_byte 224 33 0 drop_writes: All write I/O is silently ignored.
Quoted 13 lines · Mike Snitzer
Signed-off-by Mike Snitzer <[email protected]>--- Documentation/device-mapper/dm-flakey.txt | 15 ++++++++++++++- 1 files changed, 14 insertions(+), 1 deletions(-)Documentation/device-mapper/dm-flakey.txt +0
-0@@ -27,7 +27,20 @@ Mandatory parameters: Optional feature parameters: If no feature parameters are present, during the periods of
Documentation/device-mapper/dm-flakey.txt Mandatory parameters: · line 38
Quoted 10 lines
Documentation/device-mapper/dm-flakey.txt +9
-1- unreliability, all I/O returns errors. + unreliability, all I/O returns errors. Optional features may be + combined (e.g. corrupt_bio_byte on READ and drop_writes). Conflicting + features (e.g. corrupt_bio_byte on WRITE and drop_writes) are resolved + according to the following feature precedence (descending order): + + corrupt_bio_byte <Nth byte> <bio_flags> <value>: + Corrupt bios that have specific bi_rw flag(s), e.g.: READ=0 or + REQ_WRITE=1|REQ_META=32, by writing <value> to the <Nth byte> of + bios that have data.
Gah, we should also add:
<value> may be 0 or 1. Bios that don't match <bio_flags> fall through to the other optional feature(s) or the default of returning I/O error.
Quoted 13 lines
Documentation/device-mapper/dm-flakey.txt +5
-1+ Examples: + 1) corrupt 32nd byte in READ bios with the value 1: + corrupt_bio_byte 32 0 1 + 2) corrupt 224th byte in WRITE|REQ_META bios with the value 0: + corrupt_bio_byte 224 33 0 drop_writes: All write I/O is silently ignored. --dm-devel mailing list
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