diff options
Diffstat (limited to 'fs/ext4/ext4.h')
| -rw-r--r-- | fs/ext4/ext4.h | 30 |
1 files changed, 29 insertions, 1 deletions
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 70aa951..2e9a203 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -952,6 +952,7 @@ struct ext4_sb_info { atomic_t s_mb_lost_chunks; atomic_t s_mb_preallocated; atomic_t s_mb_discarded; + atomic_t s_lock_busy; /* locality groups */ struct ext4_locality_group *s_locality_groups; @@ -1593,15 +1594,42 @@ struct ext4_group_info { #define EXT4_MB_GRP_NEED_INIT(grp) \ (test_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &((grp)->bb_state))) +#define EXT4_MAX_CONTENTION 8 +#define EXT4_CONTENTION_THRESHOLD 2 + static inline spinlock_t *ext4_group_lock_ptr(struct super_block *sb, ext4_group_t group) { return bgl_lock_ptr(EXT4_SB(sb)->s_blockgroup_lock, group); } +/* + * Returns true if the filesystem is busy enough that attempts to + * access the block group locks has run into contention. + */ +static inline int ext4_fs_is_busy(struct ext4_sb_info *sbi) +{ + return (atomic_read(&sbi->s_lock_busy) > EXT4_CONTENTION_THRESHOLD); +} + static inline void ext4_lock_group(struct super_block *sb, ext4_group_t group) { - spin_lock(ext4_group_lock_ptr(sb, group)); + spinlock_t *lock = ext4_group_lock_ptr(sb, group); + if (spin_trylock(lock)) + /* + * We're able to grab the lock right away, so drop the + * lock contention counter. + */ + atomic_add_unless(&EXT4_SB(sb)->s_lock_busy, -1, 0); + else { + /* + * The lock is busy, so bump the contention counter, + * and then wait on the spin lock. + */ + atomic_add_unless(&EXT4_SB(sb)->s_lock_busy, 1, + EXT4_MAX_CONTENTION); + spin_lock(lock); + } } static inline void ext4_unlock_group(struct super_block *sb, |