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author | Linus Torvalds <torvalds@linux-foundation.org> | 2019-07-16 12:21:41 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-07-16 12:21:41 -0700 |
commit | c309b6f24222246c18a8b65d3950e6e755440865 (patch) | |
tree | 11893170f5c246bb0dee8066e85878af04162ab0 /Documentation/admin-guide/device-mapper/dm-flakey.rst | |
parent | 3e859477a1db52a0435d06a55fdb54f62d69c292 (diff) | |
parent | 168869492e7009b6861b615f1d030c99bc805e83 (diff) | |
download | linux-c309b6f24222246c18a8b65d3950e6e755440865.tar.gz linux-c309b6f24222246c18a8b65d3950e6e755440865.tar.bz2 linux-c309b6f24222246c18a8b65d3950e6e755440865.zip |
Merge tag 'docs/v5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media
Pull rst conversion of docs from Mauro Carvalho Chehab:
"As agreed with Jon, I'm sending this big series directly to you, c/c
him, as this series required a special care, in order to avoid
conflicts with other trees"
* tag 'docs/v5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (77 commits)
docs: kbuild: fix build with pdf and fix some minor issues
docs: block: fix pdf output
docs: arm: fix a breakage with pdf output
docs: don't use nested tables
docs: gpio: add sysfs interface to the admin-guide
docs: locking: add it to the main index
docs: add some directories to the main documentation index
docs: add SPDX tags to new index files
docs: add a memory-devices subdir to driver-api
docs: phy: place documentation under driver-api
docs: serial: move it to the driver-api
docs: driver-api: add remaining converted dirs to it
docs: driver-api: add xilinx driver API documentation
docs: driver-api: add a series of orphaned documents
docs: admin-guide: add a series of orphaned documents
docs: cgroup-v1: add it to the admin-guide book
docs: aoe: add it to the driver-api book
docs: add some documentation dirs to the driver-api book
docs: driver-model: move it to the driver-api book
docs: lp855x-driver.rst: add it to the driver-api book
...
Diffstat (limited to 'Documentation/admin-guide/device-mapper/dm-flakey.rst')
-rw-r--r-- | Documentation/admin-guide/device-mapper/dm-flakey.rst | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/Documentation/admin-guide/device-mapper/dm-flakey.rst b/Documentation/admin-guide/device-mapper/dm-flakey.rst new file mode 100644 index 000000000000..86138735879d --- /dev/null +++ b/Documentation/admin-guide/device-mapper/dm-flakey.rst @@ -0,0 +1,74 @@ +========= +dm-flakey +========= + +This target is the same as the linear target except that it exhibits +unreliable behaviour periodically. It's been found useful in simulating +failing devices for testing purposes. + +Starting from the time the table is loaded, the device is available for +<up interval> seconds, then exhibits unreliable behaviour for <down +interval> seconds, and then this cycle repeats. + +Also, consider using this in combination with the dm-delay target too, +which can delay reads and writes and/or send them to different +underlying devices. + +Table parameters +---------------- + +:: + + <dev path> <offset> <up interval> <down interval> \ + [<num_features> [<feature arguments>]] + +Mandatory parameters: + + <dev path>: + Full pathname to the underlying block-device, or a + "major:minor" device-number. + <offset>: + Starting sector within the device. + <up interval>: + Number of seconds device is available. + <down interval>: + Number of seconds device returns errors. + +Optional feature parameters: + + If no feature parameters are present, during the periods of + unreliability, all I/O returns errors. + + drop_writes: + All write I/O is silently ignored. + Read I/O is handled correctly. + + error_writes: + All write I/O is failed with an error signalled. + Read I/O is handled correctly. + + corrupt_bio_byte <Nth_byte> <direction> <value> <flags>: + During <down interval>, replace <Nth_byte> of the data of + each matching bio with <value>. + + <Nth_byte>: + The offset of the byte to replace. + Counting starts at 1, to replace the first byte. + <direction>: + Either 'r' to corrupt reads or 'w' to corrupt writes. + 'w' is incompatible with drop_writes. + <value>: + The value (from 0-255) to write. + <flags>: + Perform the replacement only if bio->bi_opf has all the + selected flags set. + +Examples: + +Replaces the 32nd byte of READ bios with the value 1:: + + corrupt_bio_byte 32 r 1 0 + +Replaces the 224th byte of REQ_META (=32) bios with the value 0:: + + corrupt_bio_byte 224 w 0 32 |