diff options
-rw-r--r-- | fs/super.c | 2 | ||||
-rw-r--r-- | fs/sync.c | 28 | ||||
-rw-r--r-- | include/linux/fs.h | 2 |
3 files changed, 5 insertions, 27 deletions
diff --git a/fs/super.c b/fs/super.c index 0390461dfca0..ba99524998f7 100644 --- a/fs/super.c +++ b/fs/super.c | |||
@@ -130,7 +130,7 @@ static inline void destroy_super(struct super_block *s) | |||
130 | * Drop a superblock's refcount. Returns non-zero if the superblock was | 130 | * Drop a superblock's refcount. Returns non-zero if the superblock was |
131 | * destroyed. The caller must hold sb_lock. | 131 | * destroyed. The caller must hold sb_lock. |
132 | */ | 132 | */ |
133 | static int __put_super(struct super_block *sb) | 133 | int __put_super(struct super_block *sb) |
134 | { | 134 | { |
135 | int ret = 0; | 135 | int ret = 0; |
136 | 136 | ||
@@ -80,35 +80,15 @@ EXPORT_SYMBOL_GPL(sync_filesystem); | |||
80 | /* | 80 | /* |
81 | * Sync all the data for all the filesystems (called by sys_sync() and | 81 | * Sync all the data for all the filesystems (called by sys_sync() and |
82 | * emergency sync) | 82 | * emergency sync) |
83 | * | ||
84 | * This operation is careful to avoid the livelock which could easily happen | ||
85 | * if two or more filesystems are being continuously dirtied. s_need_sync | ||
86 | * is used only here. We set it against all filesystems and then clear it as | ||
87 | * we sync them. So redirtied filesystems are skipped. | ||
88 | * | ||
89 | * But if process A is currently running sync_filesystems and then process B | ||
90 | * calls sync_filesystems as well, process B will set all the s_need_sync | ||
91 | * flags again, which will cause process A to resync everything. Fix that with | ||
92 | * a local mutex. | ||
93 | */ | 83 | */ |
94 | static void sync_filesystems(int wait) | 84 | static void sync_filesystems(int wait) |
95 | { | 85 | { |
96 | struct super_block *sb; | 86 | struct super_block *sb, *n; |
97 | static DEFINE_MUTEX(mutex); | ||
98 | 87 | ||
99 | mutex_lock(&mutex); /* Could be down_interruptible */ | ||
100 | spin_lock(&sb_lock); | 88 | spin_lock(&sb_lock); |
101 | list_for_each_entry(sb, &super_blocks, s_list) | 89 | list_for_each_entry_safe(sb, n, &super_blocks, s_list) { |
102 | if (!list_empty(&sb->s_instances)) | ||
103 | sb->s_need_sync = 1; | ||
104 | |||
105 | restart: | ||
106 | list_for_each_entry(sb, &super_blocks, s_list) { | ||
107 | if (list_empty(&sb->s_instances)) | 90 | if (list_empty(&sb->s_instances)) |
108 | continue; | 91 | continue; |
109 | if (!sb->s_need_sync) | ||
110 | continue; | ||
111 | sb->s_need_sync = 0; | ||
112 | sb->s_count++; | 92 | sb->s_count++; |
113 | spin_unlock(&sb_lock); | 93 | spin_unlock(&sb_lock); |
114 | 94 | ||
@@ -119,11 +99,9 @@ restart: | |||
119 | 99 | ||
120 | /* restart only when sb is no longer on the list */ | 100 | /* restart only when sb is no longer on the list */ |
121 | spin_lock(&sb_lock); | 101 | spin_lock(&sb_lock); |
122 | if (__put_super_and_need_restart(sb)) | 102 | __put_super(sb); |
123 | goto restart; | ||
124 | } | 103 | } |
125 | spin_unlock(&sb_lock); | 104 | spin_unlock(&sb_lock); |
126 | mutex_unlock(&mutex); | ||
127 | } | 105 | } |
128 | 106 | ||
129 | /* | 107 | /* |
diff --git a/include/linux/fs.h b/include/linux/fs.h index 62f84d955b83..e1c7427802b8 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h | |||
@@ -1332,7 +1332,6 @@ struct super_block { | |||
1332 | struct rw_semaphore s_umount; | 1332 | struct rw_semaphore s_umount; |
1333 | struct mutex s_lock; | 1333 | struct mutex s_lock; |
1334 | int s_count; | 1334 | int s_count; |
1335 | int s_need_sync; | ||
1336 | atomic_t s_active; | 1335 | atomic_t s_active; |
1337 | #ifdef CONFIG_SECURITY | 1336 | #ifdef CONFIG_SECURITY |
1338 | void *s_security; | 1337 | void *s_security; |
@@ -1780,6 +1779,7 @@ extern int get_sb_pseudo(struct file_system_type *, char *, | |||
1780 | struct vfsmount *mnt); | 1779 | struct vfsmount *mnt); |
1781 | extern void simple_set_mnt(struct vfsmount *mnt, struct super_block *sb); | 1780 | extern void simple_set_mnt(struct vfsmount *mnt, struct super_block *sb); |
1782 | int __put_super_and_need_restart(struct super_block *sb); | 1781 | int __put_super_and_need_restart(struct super_block *sb); |
1782 | int __put_super(struct super_block *sb); | ||
1783 | void put_super(struct super_block *sb); | 1783 | void put_super(struct super_block *sb); |
1784 | 1784 | ||
1785 | /* Alas, no aliases. Too much hassle with bringing module.h everywhere */ | 1785 | /* Alas, no aliases. Too much hassle with bringing module.h everywhere */ |