linux/fs/btrfs
Chris Mason bd56b30205 Btrfs: Make btrfs_drop_snapshot work in larger and more efficient chunks
Every transaction in btrfs creates a new snapshot, and then schedules the
snapshot from the last transaction for deletion.  Snapshot deletion
works by walking down the btree and dropping the reference counts
on each btree block during the walk.

If if a given leaf or node has a reference count greater than one,
the reference count is decremented and the subtree pointed to by that
node is ignored.

If the reference count is one, walking continues down into that node
or leaf, and the references of everything it points to are decremented.

The old code would try to work in small pieces, walking down the tree
until it found the lowest leaf or node to free and then returning.  This
was very friendly to the rest of the FS because it didn't have a huge
impact on other operations.

But it wouldn't always keep up with the rate that new commits added new
snapshots for deletion, and it wasn't very optimal for the extent
allocation tree because it wasn't finding leaves that were close together
on disk and processing them at the same time.

This changes things to walk down to a level 1 node and then process it
in bulk.  All the leaf pointers are sorted and the leaves are dropped
in order based on their extent number.

The extent allocation tree and commit code are now fast enough for
this kind of bulk processing to work without slowing the rest of the FS
down.  Overall it does less IO and is better able to keep up with
snapshot deletions under high load.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
2009-02-04 09:27:02 -05:00
..
acl.c Btrfs: Fix checkpatch.pl warnings 2009-01-05 21:25:51 -05:00
async-thread.c Btrfs: async threads should try harder to find work 2009-02-04 09:23:24 -05:00
async-thread.h Btrfs: Add ordered async work queues 2008-11-06 22:03:00 -05:00
btrfs_inode.h Btrfs: fix leaking block group on balance 2008-12-11 16:30:39 -05:00
compat.h Btrfs: drop remaining LINUX_KERNEL_VERSION checks and compat code 2009-01-06 09:38:55 -05:00
compression.c Btrfs: removed unused #include <version.h>'s 2009-01-21 10:49:16 -05:00
compression.h Btrfs: Add zlib compression support 2008-10-29 14:49:59 -04:00
crc32c.h Btrfs: Drop the hardware crc32c asm code 2009-01-07 19:56:59 -05:00
ctree.c Btrfs: Change btree locking to use explicit blocking points 2009-02-04 09:25:08 -05:00
ctree.h Btrfs: Change btree locking to use explicit blocking points 2009-02-04 09:25:08 -05:00
dir-item.c Btrfs: Fix checkpatch.pl warnings 2009-01-05 21:25:51 -05:00
disk-io.c Btrfs: Change btree locking to use explicit blocking points 2009-02-04 09:25:08 -05:00
disk-io.h Btrfs: fix tree logs parallel sync 2009-01-21 12:54:03 -05:00
export.c Btrfs: Fix checkpatch.pl warnings 2009-01-05 21:25:51 -05:00
export.h NFS support for btrfs - v3 2008-09-25 11:04:06 -04:00
extent_io.c Btrfs: Change btree locking to use explicit blocking points 2009-02-04 09:25:08 -05:00
extent_io.h Btrfs: Change btree locking to use explicit blocking points 2009-02-04 09:25:08 -05:00
extent_map.c Btrfs: removed unused #include <version.h>'s 2009-01-21 10:49:16 -05:00
extent_map.h Btrfs: Fix csum error for compressed data 2008-11-10 07:34:43 -05:00
extent-tree.c Btrfs: Make btrfs_drop_snapshot work in larger and more efficient chunks 2009-02-04 09:27:02 -05:00
file-item.c Btrfs: tree logging checksum fixes 2009-01-06 11:42:00 -05:00
file.c Btrfs: fix tree logs parallel sync 2009-01-21 12:54:03 -05:00
free-space-cache.c Btrfs: Fix checkpatch.pl warnings 2009-01-05 21:25:51 -05:00
hash.h Switch btrfs_name_hash() to crc32c 2008-09-25 11:04:06 -04:00
inode-item.c Btrfs: make things static and include the right headers 2008-12-02 09:54:17 -05:00
inode-map.c Btrfs: Fix checkpatch.pl warnings 2009-01-05 21:25:51 -05:00
inode.c Btrfs: Make btrfs_drop_snapshot work in larger and more efficient chunks 2009-02-04 09:27:02 -05:00
ioctl.c Btrfs: removed unused #include <version.h>'s 2009-01-21 10:49:16 -05:00
ioctl.h Btrfs: fix ioctl arg size (userland incompatible change!) 2009-01-16 11:59:08 -05:00
Kconfig Btrfs: make btrfs acls selectable 2009-02-04 09:28:28 -05:00
locking.c Btrfs: Change btree locking to use explicit blocking points 2009-02-04 09:25:08 -05:00
locking.h Btrfs: Change btree locking to use explicit blocking points 2009-02-04 09:25:08 -05:00
Makefile Btrfs: Add zlib compression support 2008-10-29 14:49:59 -04:00
ordered-data.c Btrfs: simplify iteration codes 2009-01-21 10:59:08 -05:00
ordered-data.h Btrfs: move data checksumming into a dedicated tree 2008-12-08 16:58:54 -05:00
orphan.c Btrfs: Create orphan inode records to prevent lost files after a crash 2008-09-25 11:04:05 -04:00
print-tree.c Btrfs: Fix checkpatch.pl warnings 2009-01-05 21:25:51 -05:00
print-tree.h Btrfs: Create extent_buffer interface for large blocksizes 2008-09-25 11:03:56 -04:00
ref-cache.c Btrfs: Make btrfs_drop_snapshot work in larger and more efficient chunks 2009-02-04 09:27:02 -05:00
ref-cache.h Btrfs: Make btrfs_drop_snapshot work in larger and more efficient chunks 2009-02-04 09:27:02 -05:00
root-tree.c Btrfs: Fix checkpatch.pl warnings 2009-01-05 21:25:51 -05:00
struct-funcs.c Btrfs: Fix checkpatch.pl warnings 2009-01-05 21:25:51 -05:00
super.c Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable 2009-01-28 20:29:43 -05:00
sysfs.c Btrfs: Fix checkpatch.pl warnings 2009-01-05 21:25:51 -05:00
transaction.c Btrfs: simplify iteration codes 2009-01-21 10:59:08 -05:00
transaction.h Btrfs: Fix checkpatch.pl warnings 2009-01-05 21:25:51 -05:00
tree-defrag.c Btrfs: Change btree locking to use explicit blocking points 2009-02-04 09:25:08 -05:00
tree-log.c Btrfs: Change btree locking to use explicit blocking points 2009-02-04 09:25:08 -05:00
tree-log.h Btrfs: Add a write ahead tree log to optimize synchronous operations 2008-09-25 11:04:07 -04:00
version.h Update Btrfs files for in-kernel usage 2008-09-25 15:41:59 -04:00
version.sh Btrfs: Fixes for 2.6.28-rc API changes 2008-11-19 21:17:22 -05:00
volumes.c Btrfs: Catch missed bios in the async bio submission thread 2009-02-04 09:19:41 -05:00
volumes.h Btrfs: shared seed device 2008-12-12 10:03:26 -05:00
xattr.c Btrfs: selinux support 2009-02-04 09:29:13 -05:00
xattr.h Btrfs: selinux support 2009-02-04 09:29:13 -05:00
zlib.c Btrfs: Fix checkpatch.pl warnings 2009-01-05 21:25:51 -05:00