"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@xxxxxxxxx> --- .../admin-guide/device-mapper/dm-integrity.rst | 13 +++++++++---- 1 file 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 -- 2.34.1
