XFS development tree branch, xfs-allow-logical-sector-sized-O_DIRECT, created. xfs-for-linus-v3.14-rc1-3-g7c71ee7
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The branch, xfs-allow-logical-sector-sized-O_DIRECT has been created
at 7c71ee78031c248dca13fc94dea9a4cc217db6cf (commit)
- Log ----------------------------------------------------------------- commit 7c71ee78031c248dca13fc94dea9a4cc217db6cf
Author: Eric Sandeen <[email protected]> Date: Tue Jan 21 16:46:23 2014 -0600
xfs: allow logical-sector sized O_DIRECT
Some time ago, mkfs.xfs started picking the storage physical sector size as the default filesystem "sector size" in order to avoid RMW costs incurred by doing IOs at logical sector size alignments.
However, this means that for a filesystem made with i.e. a 4k sector size on an "advanced format" 4k/512 disk, 512-byte direct IOs are no longer allowed. This means that XFS has essentially turned this AF drive into a hard 4K device, from the filesystem on up.
XFS's mkfs-specified "sector size" is really just controlling the minimum size & alignment of filesystem metadata.
There is no real need to tightly couple XFS's minimal metadata size to the minimum allowed direct IO size; XFS can continue doing metadata in optimal sizes, but still allow smaller DIOs for apps which issue them, for whatever reason.
This patch adds a new field to the xfs_buftarg, so that we now track 2 sizes:
1) The metadata sector size, which is the minimum unit and alignment of IO which will be performed by metadata operations.
2) The device logical sector size
The first is used internally by the file system for metadata alignment and IOs.
The second is used for the minimum allowed direct IO alignment.
This has passed xfstests on filesystems made with 4k sectors, including when run under the patch I sent to ignore XFS_IOC_DIOINFO, and issue 512 DIOs anyway. I also directly tested end of block behavior on preallocated, sparse, and existing files when we do a 512 IO into a 4k file on a 4k-sector filesystem, to be sure there were no unexpected behaviors.
commit 6da54179b3f1bb6a302fd5f3b38fae32ee463ed1
Author: Eric Sandeen <[email protected]> Date: Tue Jan 21 16:45:52 2014 -0600
xfs: rename xfs_buftarg structure members
In preparation for adding new members to the structure, give these old ones more descriptive names:
bt_ssize -> bt_meta_sectorsize
bt_smask -> bt_meta_sectormask
commit f0bc9985fe8bf4377d5557cd7957d9be43ec8861
Author: Eric Sandeen <[email protected]> Date: Tue Jan 21 16:44:57 2014 -0600
xfs: clean up xfs_buftarg
Clean up the xfs_buftarg structure a bit:
- remove bt_bsize which is never used
- replace bt_sshift with bt_ssize; we only ever shift it back
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