doc: Convert the posix translator documentation to markdown

Change-Id: I6b6c3b2063c81e8799c3273434119dd9bff1be79
Signed-off-by: Lubomir Rintel <lubo.rintel@gooddata.com>
Reviewed-on: http://review.gluster.org/5486
Reviewed-by: Vijay Bellur <vbellur@redhat.com>
Tested-by: Vijay Bellur <vbellur@redhat.com>

1 files changed, 59 insertions, 0 deletions

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+storage/posix translator
+========================
+
+Notes
+-----
+
+### `SET_FS_ID`
+
+This is so that all filesystem checks are done with the user's
+uid/gid and not GlusterFS's uid/gid.
+
+### `MAKE_REAL_PATH`
+
+This macro concatenates the base directory of the posix volume
+('option directory') with the given path.
+
+### `need_xattr` in lookup
+
+If this flag is passed, lookup returns a xattr dictionary that contains
+the file's create time, the file's contents, and the version number
+of the file.
+
+This is a hack to increase small file performance. If an application
+wants to read a small file, it can finish its job with just a lookup
+call instead of a lookup followed by read.
+
+### `getdents`/`setdents`
+
+These are used by unify to set and get directory entries.
+
+### `ALIGN_BUF`
+
+Macro to align an address to a page boundary (4K).
+
+### `priv->export_statfs`
+
+In some cases, two exported volumes may reside on the same
+partition on the server. Sending statvfs info for both
+the volumes will lead to erroneous df output at the client,
+since free space on the partition will be counted twice.
+
+In such cases, user can disable exporting statvfs info
+on one of the volumes by setting this option.
+
+### `xattrop`
+
+This fop is used by replicate to set version numbers on files.
+
+### `getxattr`/`setxattr` hack to read/write files
+
+A key, `GLUSTERFS_FILE_CONTENT_STRING`, is handled in a special way by
+`getxattr`/`setxattr`. A getxattr with the key will return the entire
+content of the file as the value. A `setxattr` with the key will write
+the value as the entire content of the file.
+
+### `posix_checksum`
+
+This calculates a simple XOR checksum on all entry names in a
+directory that is used by unify to compare directory contents.