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author | Russell Harmon <eatnumber1@gmail.com> | 2023-06-05 08:08:51 +0300 |
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committer | Mike Snitzer <snitzer@kernel.org> | 2023-06-23 01:39:50 +0300 |
commit | 3b671459e687e6b7d3f87d39a0b242bbebf871be (patch) | |
tree | e6b06badbfafbb932d859fa5feff0207bf41f7e0 /Documentation | |
parent | c3ba5aa6f789097364398ad38fe541841bade17d (diff) | |
download | linux-3b671459e687e6b7d3f87d39a0b242bbebf871be.tar.xz |
Documentation: dm-integrity: Document the meaning of "buffer".
"Buffers" are buffers of the metadata/checksum area of dm-integrity.
They are always at most as large as a single metadata area on-disk, but
may be smaller.
Signed-off-by: Russell Harmon <eatnumber1@gmail.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/admin-guide/device-mapper/dm-integrity.rst | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/Documentation/admin-guide/device-mapper/dm-integrity.rst b/Documentation/admin-guide/device-mapper/dm-integrity.rst index b2a698e955a3..31f514675809 100644 --- a/Documentation/admin-guide/device-mapper/dm-integrity.rst +++ b/Documentation/admin-guide/device-mapper/dm-integrity.rst @@ -38,6 +38,15 @@ the device. But it will only format the device if the superblock contains zeroes. If the superblock is neither valid nor zeroed, the dm-integrity target can't be loaded. +Accesses to the on-disk metadata area containing checksums (aka tags) are +buffered using dm-bufio. When an access to any given metadata area +occurs, each unique metadata area gets its own buffer(s). The buffer size +is capped at the size of the metadata area, but may be smaller, thereby +requiring multiple buffers to represent the full metadata area. A smaller +buffer size will produce a smaller resulting read/write operation to the +metadata area for small reads/writes. The metadata is still read even in +a full write to the data covered by a single buffer. + To use the target for the first time: 1. overwrite the superblock with zeroes @@ -106,10 +115,6 @@ buffer_sectors:number The number of sectors in one buffer. The value is rounded down to a power of two. - The tag area is accessed using buffers, the buffer size is - configurable. The large buffer size means that the I/O size will - be larger, but there could be less I/Os issued. - journal_watermark:number The journal watermark in percents. When the size of the journal exceeds this watermark, the thread that flushes the journal will |