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-rw-r--r--fs/fs-writeback.c28
-rw-r--r--fs/internal.h1
-rw-r--r--fs/super.c33
3 files changed, 35 insertions, 27 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 0f015a0468d..b8c507ca42f 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -461,32 +461,6 @@ writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
}
/*
- * For background writeback the caller does not have the sb pinned
- * before calling writeback. So make sure that we do pin it, so it doesn't
- * go away while we are writing inodes from it.
- */
-static bool pin_sb_for_writeback(struct super_block *sb)
-{
- spin_lock(&sb_lock);
- if (list_empty(&sb->s_instances)) {
- spin_unlock(&sb_lock);
- return false;
- }
-
- sb->s_count++;
- spin_unlock(&sb_lock);
-
- if (down_read_trylock(&sb->s_umount)) {
- if (sb->s_root)
- return true;
- up_read(&sb->s_umount);
- }
-
- put_super(sb);
- return false;
-}
-
-/*
* Write a portion of b_io inodes which belong to @sb.
*
* If @only_this_sb is true, then find and write all such
@@ -585,7 +559,7 @@ void writeback_inodes_wb(struct bdi_writeback *wb,
struct inode *inode = wb_inode(wb->b_io.prev);
struct super_block *sb = inode->i_sb;
- if (!pin_sb_for_writeback(sb)) {
+ if (!grab_super_passive(sb)) {
requeue_io(inode);
continue;
}
diff --git a/fs/internal.h b/fs/internal.h
index ae47c48bedd..fe327c20af8 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -97,6 +97,7 @@ extern struct file *get_empty_filp(void);
* super.c
*/
extern int do_remount_sb(struct super_block *, int, void *, int);
+extern bool grab_super_passive(struct super_block *sb);
extern void __put_super(struct super_block *sb);
extern void put_super(struct super_block *sb);
extern struct dentry *mount_fs(struct file_system_type *,
diff --git a/fs/super.c b/fs/super.c
index 73ab9f9b357..e63c754447c 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -243,6 +243,39 @@ static int grab_super(struct super_block *s) __releases(sb_lock)
}
/*
+ * grab_super_passive - acquire a passive reference
+ * @s: reference we are trying to grab
+ *
+ * Tries to acquire a passive reference. This is used in places where we
+ * cannot take an active reference but we need to ensure that the
+ * superblock does not go away while we are working on it. It returns
+ * false if a reference was not gained, and returns true with the s_umount
+ * lock held in read mode if a reference is gained. On successful return,
+ * the caller must drop the s_umount lock and the passive reference when
+ * done.
+ */
+bool grab_super_passive(struct super_block *sb)
+{
+ spin_lock(&sb_lock);
+ if (list_empty(&sb->s_instances)) {
+ spin_unlock(&sb_lock);
+ return false;
+ }
+
+ sb->s_count++;
+ spin_unlock(&sb_lock);
+
+ if (down_read_trylock(&sb->s_umount)) {
+ if (sb->s_root)
+ return true;
+ up_read(&sb->s_umount);
+ }
+
+ put_super(sb);
+ return false;
+}
+
+/*
* Superblock locking. We really ought to get rid of these two.
*/
void lock_super(struct super_block * sb)