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-rw-r--r--fs/super.c69
1 files changed, 65 insertions, 4 deletions
diff --git a/fs/super.c b/fs/super.c
index b03fea8fbfb6..19eb70b374bc 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -54,7 +54,7 @@ DEFINE_SPINLOCK(sb_lock);
static struct super_block *alloc_super(struct file_system_type *type)
{
struct super_block *s = kzalloc(sizeof(struct super_block), GFP_USER);
- static struct super_operations default_op;
+ static const struct super_operations default_op;
if (s) {
if (security_sb_alloc(s)) {
@@ -465,6 +465,48 @@ rescan:
}
EXPORT_SYMBOL(get_super);
+
+/**
+ * get_active_super - get an active reference to the superblock of a device
+ * @bdev: device to get the superblock for
+ *
+ * Scans the superblock list and finds the superblock of the file system
+ * mounted on the device given. Returns the superblock with an active
+ * reference and s_umount held exclusively or %NULL if none was found.
+ */
+struct super_block *get_active_super(struct block_device *bdev)
+{
+ struct super_block *sb;
+
+ if (!bdev)
+ return NULL;
+
+ spin_lock(&sb_lock);
+ list_for_each_entry(sb, &super_blocks, s_list) {
+ if (sb->s_bdev != bdev)
+ continue;
+
+ sb->s_count++;
+ spin_unlock(&sb_lock);
+ down_write(&sb->s_umount);
+ if (sb->s_root) {
+ spin_lock(&sb_lock);
+ if (sb->s_count > S_BIAS) {
+ atomic_inc(&sb->s_active);
+ sb->s_count--;
+ spin_unlock(&sb_lock);
+ return sb;
+ }
+ spin_unlock(&sb_lock);
+ }
+ up_write(&sb->s_umount);
+ put_super(sb);
+ yield();
+ spin_lock(&sb_lock);
+ }
+ spin_unlock(&sb_lock);
+ return NULL;
+}
struct super_block * user_get_super(dev_t dev)
{
@@ -527,11 +569,15 @@ int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
{
int retval;
int remount_rw;
-
+
+ if (sb->s_frozen != SB_UNFROZEN)
+ return -EBUSY;
+
#ifdef CONFIG_BLOCK
if (!(flags & MS_RDONLY) && bdev_read_only(sb->s_bdev))
return -EACCES;
#endif
+
if (flags & MS_RDONLY)
acct_auto_close(sb);
shrink_dcache_sb(sb);
@@ -743,9 +789,14 @@ int get_sb_bdev(struct file_system_type *fs_type,
* will protect the lockfs code from trying to start a snapshot
* while we are mounting
*/
- down(&bdev->bd_mount_sem);
+ mutex_lock(&bdev->bd_fsfreeze_mutex);
+ if (bdev->bd_fsfreeze_count > 0) {
+ mutex_unlock(&bdev->bd_fsfreeze_mutex);
+ error = -EBUSY;
+ goto error_bdev;
+ }
s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
- up(&bdev->bd_mount_sem);
+ mutex_unlock(&bdev->bd_fsfreeze_mutex);
if (IS_ERR(s))
goto error_s;
@@ -892,6 +943,16 @@ vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void
if (error)
goto out_sb;
+ /*
+ * filesystems should never set s_maxbytes larger than MAX_LFS_FILESIZE
+ * but s_maxbytes was an unsigned long long for many releases. Throw
+ * this warning for a little while to try and catch filesystems that
+ * violate this rule. This warning should be either removed or
+ * converted to a BUG() in 2.6.34.
+ */
+ WARN((mnt->mnt_sb->s_maxbytes < 0), "%s set sb->s_maxbytes to "
+ "negative value (%lld)\n", type->name, mnt->mnt_sb->s_maxbytes);
+
mnt->mnt_mountpoint = mnt->mnt_root;
mnt->mnt_parent = mnt;
up_write(&mnt->mnt_sb->s_umount);