dm flakey: document corrupt_bio_byte and optional feature precedence
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
--- Documentation/device-mapper/dm-flakey.txt | 15 ++++++++++++++- 1 files changed, 14 insertions(+), 1 deletions(-) diff --git a/Documentation/device-mapper/dm-flakey.txt b/Documentation/device-mapper/dm-flakey.txt index 6b40f79..6b4df49 100644 --- a/Documentation/device-mapper/dm-flakey.txt +++ b/Documentation/device-mapper/dm-flakey.txt @@ -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. -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel |
dm flakey: document corrupt_bio_byte and optional feature precedence
On Wed, Jun 29 2011 at 10:41am -0400,
Mike Snitzer <snitzer@redhat.com> wrote: > Signed-off-by: Mike Snitzer <snitzer@redhat.com> > --- > Documentation/device-mapper/dm-flakey.txt | 15 ++++++++++++++- > 1 files changed, 14 insertions(+), 1 deletions(-) > > diff --git a/Documentation/device-mapper/dm-flakey.txt b/Documentation/device-mapper/dm-flakey.txt > index 6b40f79..6b4df49 100644 > --- a/Documentation/device-mapper/dm-flakey.txt > +++ b/Documentation/device-mapper/dm-flakey.txt > @@ -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. 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. > + 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 > dm-devel@redhat.com > https://www.redhat.com/mailman/listinfo/dm-devel -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel |
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