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-rw-r--r--Documentation/ABI/testing/sysfs-fs-ext413
-rw-r--r--Documentation/filesystems/ext4.txt10
2 files changed, 23 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-fs-ext4 b/Documentation/ABI/testing/sysfs-fs-ext4
index f22ac0872ae8..c631253cf85c 100644
--- a/Documentation/ABI/testing/sysfs-fs-ext4
+++ b/Documentation/ABI/testing/sysfs-fs-ext4
@@ -96,3 +96,16 @@ Contact: "Theodore Ts'o" <tytso@mit.edu>
Description:
The maximum number of megabytes the writeback code will
try to write out before move on to another inode.
+
+What: /sys/fs/ext4/<disk>/extent_max_zeroout_kb
+Date: August 2012
+Contact: "Theodore Ts'o" <tytso@mit.edu>
+Description:
+ The maximum number of kilobytes which will be zeroed
+ out in preference to creating a new uninitialized
+ extent when manipulating an inode's extent tree. Note
+ that using a larger value will increase the
+ variability of time necessary to complete a random
+ write operation (since a 4k random write might turn
+ into a much larger write due to the zeroout
+ operation).
diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt
index 1b7f9acbcbbe..104322bf378c 100644
--- a/Documentation/filesystems/ext4.txt
+++ b/Documentation/filesystems/ext4.txt
@@ -375,6 +375,16 @@ dioread_nolock locking. If the dioread_nolock option is specified
Because of the restrictions this options comprises
it is off by default (e.g. dioread_lock).
+max_dir_size_kb=n This limits the size of directories so that any
+ attempt to expand them beyond the specified
+ limit in kilobytes will cause an ENOSPC error.
+ This is useful in memory constrained
+ environments, where a very large directory can
+ cause severe performance problems or even
+ provoke the Out Of Memory killer. (For example,
+ if there is only 512mb memory available, a 176mb
+ directory may seriously cramp the system's style.)
+
i_version Enable 64-bit inode version support. This option is
off by default.