Filesystem with frozen but unlinked files cannot be forced into
a fully consistent state. Also handling of closing such files on frozen
filesystem is problematic since fput() can be called with mmap_sem held
and protection against frozen filesystem ranks above it.
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
fs/super.c | 26 +++++++++++++++++++-------
1 files changed, 19 insertions(+), 7 deletions(-)
diff --git a/fs/super.c b/fs/super.c
index 0830afb..e0f5992 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -1415,16 +1415,22 @@ int freeze_super(struct super_block *sb)
/* All writers are done so after syncing there won't be dirty data */
sync_filesystem(sb);
+ /*
+ * Check whether there are some open unlinked files (since all writers
+ * are blocked, new ones cannot be created now so the check is
+ * reliable). In that case filesystem cannot be forced into a
+ * consistent state so we just bail out.
+ */
+ if (atomic_long_read(&sb->s_remove_count)) {
+ ret = -EBUSY;
+ goto bail;
+ }
+
if (sb->s_op->freeze_fs) {
ret = sb->s_op->freeze_fs(sb);
if (ret) {
- printk(KERN_ERR
- "VFS:Filesystem freeze failed\n");
- sb->s_writers.frozen = SB_UNFROZEN;
- smp_wmb();
- wake_up(&sb->s_writers.wait_unfrozen);
- deactivate_locked_super(sb);
- return ret;
+ printk(KERN_ERR "VFS: Filesystem freeze failed\n");
+ goto bail;
}
}
/*
@@ -1434,6 +1440,12 @@ int freeze_super(struct super_block *sb)
sb->s_writers.frozen = SB_FREEZE_COMPLETE;
up_write(&sb->s_umount);
return 0;
+bail:
+ sb->s_writers.frozen = SB_UNFROZEN;
+ smp_wmb();
+ wake_up(&sb->s_writers.wait_unfrozen);
+ deactivate_locked_super(sb);
+ return ret;
}
EXPORT_SYMBOL(freeze_super);
--
1.7.1
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
