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authorRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>2009-11-12 00:13:32 +0900
committerRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>2009-11-13 10:33:24 +0900
commitc1ea985c710f41e97f1c72c29bbf367375370f0b (patch)
tree7345a5041a7ea432dcdebe664b7e57066d968e9f
parent156171c71a0dc4bce12b4408bb1591f8fe32dc1a (diff)
nilfs2: fix lock order reversal in chcp operation
Will fix the following lock order reversal lockdep detected: ======================================================= [ INFO: possible circular locking dependency detected ] 2.6.32-rc6 #7 ------------------------------------------------------- chcp/30157 is trying to acquire lock: (&nilfs->ns_mount_mutex){+.+.+.}, at: [<fed7cfcc>] nilfs_cpfile_change_cpmode+0x46/0x752 [nilfs2] but task is already holding lock: (&nilfs->ns_segctor_sem){++++.+}, at: [<fed7ca32>] nilfs_transaction_begin+0xba/0x110 [nilfs2] which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&nilfs->ns_segctor_sem){++++.+}: [<c105799c>] __lock_acquire+0x109c/0x139d [<c1057d26>] lock_acquire+0x89/0xa0 [<c14151e2>] down_read+0x31/0x45 [<fed6d77b>] nilfs_attach_checkpoint+0x8f/0x16b [nilfs2] [<fed6e393>] nilfs_get_sb+0x3e7/0x653 [nilfs2] [<c10c0ccb>] vfs_kern_mount+0x8b/0x124 [<c10c0db2>] do_kern_mount+0x37/0xc3 [<c10d7517>] do_mount+0x64d/0x69d [<c10d75cd>] sys_mount+0x66/0x95 [<c1002a14>] sysenter_do_call+0x12/0x32 -> #1 (&type->s_umount_key#31/1){+.+.+.}: [<c105799c>] __lock_acquire+0x109c/0x139d [<c1057d26>] lock_acquire+0x89/0xa0 [<c104c0f3>] down_write_nested+0x34/0x52 [<c10c08fe>] sget+0x22e/0x389 [<fed6e133>] nilfs_get_sb+0x187/0x653 [nilfs2] [<c10c0ccb>] vfs_kern_mount+0x8b/0x124 [<c10c0db2>] do_kern_mount+0x37/0xc3 [<c10d7517>] do_mount+0x64d/0x69d [<c10d75cd>] sys_mount+0x66/0x95 [<c1002a14>] sysenter_do_call+0x12/0x32 -> #0 (&nilfs->ns_mount_mutex){+.+.+.}: [<c1057727>] __lock_acquire+0xe27/0x139d [<c1057d26>] lock_acquire+0x89/0xa0 [<c1414d63>] mutex_lock_nested+0x41/0x23e [<fed7cfcc>] nilfs_cpfile_change_cpmode+0x46/0x752 [nilfs2] [<fed801b2>] nilfs_ioctl+0x11a/0x7da [nilfs2] [<c10cca12>] vfs_ioctl+0x27/0x6e [<c10ccf93>] do_vfs_ioctl+0x491/0x4db [<c10cd022>] sys_ioctl+0x45/0x5f [<c1002a14>] sysenter_do_call+0x12/0x32 Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
-rw-r--r--fs/nilfs2/cpfile.c2
-rw-r--r--fs/nilfs2/ioctl.c6
2 files changed, 5 insertions, 3 deletions
diff --git a/fs/nilfs2/cpfile.c b/fs/nilfs2/cpfile.c
index 1c6cfb59128..3f5d5d06f53 100644
--- a/fs/nilfs2/cpfile.c
+++ b/fs/nilfs2/cpfile.c
@@ -871,7 +871,6 @@ int nilfs_cpfile_change_cpmode(struct inode *cpfile, __u64 cno, int mode)
* exclusive with a new mount job. Though it doesn't cover
* umount, it's enough for the purpose.
*/
- mutex_lock(&nilfs->ns_mount_mutex);
if (nilfs_checkpoint_is_mounted(nilfs, cno, 1)) {
/* Current implementation does not have to protect
plain read-only mounts since they are exclusive
@@ -880,7 +879,6 @@ int nilfs_cpfile_change_cpmode(struct inode *cpfile, __u64 cno, int mode)
ret = -EBUSY;
} else
ret = nilfs_cpfile_clear_snapshot(cpfile, cno);
- mutex_unlock(&nilfs->ns_mount_mutex);
return ret;
case NILFS_SNAPSHOT:
return nilfs_cpfile_set_snapshot(cpfile, cno);
diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index d24057d58f1..f6af76042d8 100644
--- a/fs/nilfs2/ioctl.c
+++ b/fs/nilfs2/ioctl.c
@@ -99,7 +99,8 @@ static int nilfs_ioctl_wrap_copy(struct the_nilfs *nilfs,
static int nilfs_ioctl_change_cpmode(struct inode *inode, struct file *filp,
unsigned int cmd, void __user *argp)
{
- struct inode *cpfile = NILFS_SB(inode->i_sb)->s_nilfs->ns_cpfile;
+ struct the_nilfs *nilfs = NILFS_SB(inode->i_sb)->s_nilfs;
+ struct inode *cpfile = nilfs->ns_cpfile;
struct nilfs_transaction_info ti;
struct nilfs_cpmode cpmode;
int ret;
@@ -109,14 +110,17 @@ static int nilfs_ioctl_change_cpmode(struct inode *inode, struct file *filp,
if (copy_from_user(&cpmode, argp, sizeof(cpmode)))
return -EFAULT;
+ mutex_lock(&nilfs->ns_mount_mutex);
nilfs_transaction_begin(inode->i_sb, &ti, 0);
ret = nilfs_cpfile_change_cpmode(
cpfile, cpmode.cm_cno, cpmode.cm_mode);
if (unlikely(ret < 0)) {
nilfs_transaction_abort(inode->i_sb);
+ mutex_unlock(&nilfs->ns_mount_mutex);
return ret;
}
nilfs_transaction_commit(inode->i_sb); /* never fails */
+ mutex_unlock(&nilfs->ns_mount_mutex);
return ret;
}