path: root/Documentation/filesystems/ocfs2.txt
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authorMark Fasheh <mfasheh@suse.com>2009-12-07 13:10:48 -0800
committerJoel Becker <joel.becker@oracle.com>2010-05-05 18:17:30 -0700
commitd02f00cc057809d96c044cc72d5b9809d59f7d49 (patch)
tree44a6d81ecf9fb4b5aa91c0501a8da2ee36890a38 /Documentation/filesystems/ocfs2.txt
parentec20cec7a351584ca6c70ead012e73d61f9a8e04 (diff)
ocfs2: allocation reservations
This patch improves Ocfs2 allocation policy by allowing an inode to reserve a portion of the local alloc bitmap for itself. The reserved portion (allocation window) is advisory in that other allocation windows might steal it if the local alloc bitmap becomes full. Otherwise, the reservations are honored and guaranteed to be free. When the local alloc window is moved to a different portion of the bitmap, existing reservations are discarded. Reservation windows are represented internally by a red-black tree. Within that tree, each node represents the reservation window of one inode. An LRU of active reservations is also maintained. When new data is written, we allocate it from the inodes window. When all bits in a window are exhausted, we allocate a new one as close to the previous one as possible. Should we not find free space, an existing reservation is pulled off the LRU and cannibalized. Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Diffstat (limited to 'Documentation/filesystems/ocfs2.txt')
1 files changed, 3 insertions, 0 deletions
diff --git a/Documentation/filesystems/ocfs2.txt b/Documentation/filesystems/ocfs2.txt
index c58b9f5ba00..412df909593 100644
--- a/Documentation/filesystems/ocfs2.txt
+++ b/Documentation/filesystems/ocfs2.txt
@@ -80,3 +80,6 @@ user_xattr (*) Enables Extended User Attributes.
nouser_xattr Disables Extended User Attributes.
acl Enables POSIX Access Control Lists support.
noacl (*) Disables POSIX Access Control Lists support.
+resv_level=4 (*) Set how agressive allocation reservations will be.
+ Valid values are between 0 (reservations off) to 8
+ (maximum space for reservations).