Merge tag 'f2fs-for-6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk...

[sfrench/cifs-2.6.git] / Documentation / filesystems / f2fs.rst

diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst
index ad8dc8c040a2766d176728fe089edcf3e0950d8a..d0c09663dae859c04a50eceb89e786b2cc0e3329 100644 (file)
--- a/Documentation/filesystems/f2fs.rst
+++ b/Documentation/filesystems/f2fs.rst
@@ -336,6 +336,11 @@ discard_unit=%s             Control discard unit, the argument can be "block", "segment"
                         default, it is helpful for large sized SMR or ZNS devices to
                         reduce memory cost by getting rid of fs metadata supports small
                         discard.
+memory=%s               Control memory mode. This supports "normal" and "low" modes.
+                        "low" mode is introduced to support low memory devices.
+                        Because of the nature of low memory devices, in this mode, f2fs
+                        will try to save memory sometimes by sacrificing performance.
+                        "normal" mode is the default mode and same as before.
 ======================== ============================================================
 
 Debugfs Entries
@@ -818,10 +823,11 @@ Compression implementation
   Instead, the main goal is to reduce data writes to flash disk as much as
   possible, resulting in extending disk life time as well as relaxing IO
   congestion. Alternatively, we've added ioctl(F2FS_IOC_RELEASE_COMPRESS_BLOCKS)
-  interface to reclaim compressed space and show it to user after putting the
-  immutable bit. Immutable bit, after release, it doesn't allow writing/mmaping
-  on the file, until reserving compressed space via
-  ioctl(F2FS_IOC_RESERVE_COMPRESS_BLOCKS) or truncating filesize to zero.
+  interface to reclaim compressed space and show it to user after setting a
+  special flag to the inode. Once the compressed space is released, the flag
+  will block writing data to the file until either the compressed space is
+  reserved via ioctl(F2FS_IOC_RESERVE_COMPRESS_BLOCKS) or the file size is
+  truncated to zero.
 
 Compress metadata layout::
 
@@ -830,12 +836,12 @@ Compress metadata layout::
                | cluster 1 | cluster 2 | ......... | cluster N |
                +-----------------------------------------------+
                .           .                       .           .
-       .                       .                .                      .
+         .                      .                .                      .
     .         Compressed Cluster       .        .        Normal Cluster            .
     +----------+---------+---------+---------+  +---------+---------+---------+---------+
     |compr flag| block 1 | block 2 | block 3 |  | block 1 | block 2 | block 3 | block 4 |
     +----------+---------+---------+---------+  +---------+---------+---------+---------+
-           .                             .
+              .                             .
            .                                           .
        .                                                           .
        +-------------+-------------+----------+----------------------------+