diff options
author | merge <null@invalid> | 2009-01-22 13:55:32 +0000 |
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committer | Andy Green <agreen@octopus.localdomain> | 2009-01-22 13:55:32 +0000 |
commit | aa6f5ffbdba45aa8e19e5048648fc6c7b25376d3 (patch) | |
tree | fbb786d0ac6f8a774fd834e9ce951197e60fbffa /fs/btrfs/locking.c | |
parent | f2d78193eae5dccd3d588d2c8ea0866efc368332 (diff) |
MERGE-via-pending-tracking-hist-MERGE-via-stable-tracking-MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040-1232632141
pending-tracking-hist top was MERGE-via-stable-tracking-MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040-1232632141 / fdf777a63bcb59e0dfd78bfe2c6242e01f6d4eb9 ... parent commitmessage:
From: merge <null@invalid>
MERGE-via-stable-tracking-hist-MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040
stable-tracking-hist top was MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040 / 90463bfd2d5a3c8b52f6e6d71024a00e052b0ced ... parent commitmessage:
From: merge <null@invalid>
MERGE-via-mokopatches-tracking-hist-fix-stray-endmenu-patch
mokopatches-tracking-hist top was fix-stray-endmenu-patch / 3630e0be570de8057e7f8d2fe501ed353cdf34e6 ... parent commitmessage:
From: Andy Green <andy@openmoko.com>
fix-stray-endmenu.patch
Signed-off-by: Andy Green <andy@openmoko.com>
Diffstat (limited to 'fs/btrfs/locking.c')
-rw-r--r-- | fs/btrfs/locking.c | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c new file mode 100644 index 00000000000..39bae7761db --- /dev/null +++ b/fs/btrfs/locking.c @@ -0,0 +1,88 @@ +/* + * Copyright (C) 2008 Oracle. All rights reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public + * License v2 as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public + * License along with this program; if not, write to the + * Free Software Foundation, Inc., 59 Temple Place - Suite 330, + * Boston, MA 021110-1307, USA. + */ +#include <linux/sched.h> +#include <linux/gfp.h> +#include <linux/pagemap.h> +#include <linux/spinlock.h> +#include <linux/page-flags.h> +#include <asm/bug.h> +#include "ctree.h" +#include "extent_io.h" +#include "locking.h" + +/* + * locks the per buffer mutex in an extent buffer. This uses adaptive locks + * and the spin is not tuned very extensively. The spinning does make a big + * difference in almost every workload, but spinning for the right amount of + * time needs some help. + * + * In general, we want to spin as long as the lock holder is doing btree + * searches, and we should give up if they are in more expensive code. + */ + +int btrfs_tree_lock(struct extent_buffer *eb) +{ + int i; + + if (mutex_trylock(&eb->mutex)) + return 0; + for (i = 0; i < 512; i++) { + cpu_relax(); + if (mutex_trylock(&eb->mutex)) + return 0; + } + cpu_relax(); + mutex_lock_nested(&eb->mutex, BTRFS_MAX_LEVEL - btrfs_header_level(eb)); + return 0; +} + +int btrfs_try_tree_lock(struct extent_buffer *eb) +{ + return mutex_trylock(&eb->mutex); +} + +int btrfs_tree_unlock(struct extent_buffer *eb) +{ + mutex_unlock(&eb->mutex); + return 0; +} + +int btrfs_tree_locked(struct extent_buffer *eb) +{ + return mutex_is_locked(&eb->mutex); +} + +/* + * btrfs_search_slot uses this to decide if it should drop its locks + * before doing something expensive like allocating free blocks for cow. + */ +int btrfs_path_lock_waiting(struct btrfs_path *path, int level) +{ + int i; + struct extent_buffer *eb; + for (i = level; i <= level + 1 && i < BTRFS_MAX_LEVEL; i++) { + eb = path->nodes[i]; + if (!eb) + break; + smp_mb(); + if (!list_empty(&eb->mutex.wait_list)) + return 1; + } + return 0; +} + |