ext4: Add sysfs support

Add basic sysfs support so that information about the mounted
filesystem and various tuning parameters can be accessed via
/sys/fs/ext4/<dev>/*.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 81 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-fs-ext4 b/Documentation/ABI/testing/sysfs-fs-ext4
new file mode 100644
index 000000000000..4e79074de282
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-fs-ext4
@@ -0,0 +1,81 @@
+What:           /sys/fs/ext4/<disk>/mb_stats
+Date:           March 2008
+Contact:        "Theodore Ts'o" <tytso@mit.edu>
+Description:
+                 Controls whether the multiblock allocator should
+                 collect statistics, which are shown during the unmount.
+                 1 means to collect statistics, 0 means not to collect
+                 statistics
+
+What:           /sys/fs/ext4/<disk>/mb_group_prealloc
+Date:           March 2008
+Contact:        "Theodore Ts'o" <tytso@mit.edu>
+Description:
+                The multiblock allocator will round up allocation
+                requests to a multiple of this tuning parameter if the
+                stripe size is not set in the ext4 superblock
+
+What:           /sys/fs/ext4/<disk>/mb_max_to_scan
+Date:           March 2008
+Contact:        "Theodore Ts'o" <tytso@mit.edu>
+Description:
+                The maximum number of extents the multiblock allocator
+                will search to find the best extent
+
+What:           /sys/fs/ext4/<disk>/mb_min_to_scan
+Date:           March 2008
+Contact:        "Theodore Ts'o" <tytso@mit.edu>
+Description:
+                The minimum number of extents the multiblock allocator
+                will search to find the best extent
+
+What:           /sys/fs/ext4/<disk>/mb_order2_req
+Date:           March 2008
+Contact:        "Theodore Ts'o" <tytso@mit.edu>
+Description:
+                Tuning parameter which controls the minimum size for 
+                requests (as a power of 2) where the buddy cache is
+                used
+
+What:           /sys/fs/ext4/<disk>/mb_stream_req
+Date:           March 2008
+Contact:        "Theodore Ts'o" <tytso@mit.edu>
+Description:
+                Files which have fewer blocks than this tunable
+                parameter will have their blocks allocated out of a
+                block group specific preallocation pool, so that small
+                files are packed closely together.  Each large file
+                 will have its blocks allocated out of its own unique
+                 preallocation pool.
+
+What:           /sys/fs/ext4/<disk>/inode_readahead
+Date:           March 2008
+Contact:        "Theodore Ts'o" <tytso@mit.edu>
+Description:
+                Tuning parameter which controls the maximum number of
+                inode table blocks that ext4's inode table readahead
+                algorithm will pre-read into the buffer cache
+
+What:           /sys/fs/ext4/<disk>/delayed_allocation_blocks
+Date:           March 2008
+Contact:        "Theodore Ts'o" <tytso@mit.edu>
+Description:
+                This file is read-only and shows the number of blocks
+                that are dirty in the page cache, but which do not
+                have their location in the filesystem allocated yet.
+
+What:           /sys/fs/ext4/<disk>/lifetime_write_kbytes
+Date:           March 2008
+Contact:        "Theodore Ts'o" <tytso@mit.edu>
+Description:
+                This file is read-only and shows the number of kilobytes
+                of data that have been written to this filesystem since it was
+                created.
+
+What:           /sys/fs/ext4/<disk>/session_write_kbytes
+Date:           March 2008
+Contact:        "Theodore Ts'o" <tytso@mit.edu>
+Description:
+                This file is read-only and shows the number of
+                kilobytes of data that have been written to this
+                filesystem since it was mounted.