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ext4: prevent parallel resizers by atomic bit ops

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Before this patch, parallel resizers are allowed and protected by a
mutex lock, actually, there is no need to support parallel resizer, so
this patch prevents parallel resizers by atmoic bit ops, like
lock_page() and unlock_page() do.

To do this, the patch removed the mutex lock s_resize_lock from struct
ext4_sb_info and added a unsigned long field named s_resize_flags
which inidicates if there is a resizer.

Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Yongqiang Yang
2011-07-26 21:35:44 -04:00
committed by Theodore Ts'o
parent 2d859db3e4
commit 8f82f840ec
4 changed files with 36 additions and 40 deletions
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7
fs/ext4/ext4.h
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@@ -1127,7 +1127,8 @@ struct ext4_sb_info {
struct journal_s *s_journal;
struct list_head s_orphan;
struct mutex s_orphan_lock;
struct mutex s_resize_lock;
unsigned long s_resize_flags; /* Flags indicating if there
is a resizer */
unsigned long s_commit_interval;
u32 s_max_batch_time;
u32 s_min_batch_time;
@@ -2269,6 +2270,10 @@ static inline void set_bitmap_uptodate(struct buffer_head *bh)
extern wait_queue_head_t ext4__ioend_wq[EXT4_WQ_HASH_SZ];
extern struct mutex ext4__aio_mutex[EXT4_WQ_HASH_SZ];
#define EXT4_RESIZING 0
extern int ext4_resize_begin(struct super_block *sb);
extern void ext4_resize_end(struct super_block *sb);
#endif /* __KERNEL__ */
#endif /* _EXT4_H */