From: Greg Kroah-Hartman Date: Wed, 8 Aug 2012 15:59:30 +0000 (-0700) Subject: 3.0-stable patches X-Git-Tag: v3.5.1~2^2~5 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=a63d832d4ddec8d97bfe7771c7dc1121e8a5f087;p=thirdparty%2Fkernel%2Fstable-queue.git 3.0-stable patches added patches: nilfs2-fix-deadlock-issue-between-chcp-and-thaw-ioctls.patch --- diff --git a/queue-3.0/nilfs2-fix-deadlock-issue-between-chcp-and-thaw-ioctls.patch b/queue-3.0/nilfs2-fix-deadlock-issue-between-chcp-and-thaw-ioctls.patch new file mode 100644 index 00000000000..c60d88c3329 --- /dev/null +++ b/queue-3.0/nilfs2-fix-deadlock-issue-between-chcp-and-thaw-ioctls.patch @@ -0,0 +1,135 @@ +From 572d8b3945a31bee7c40d21556803e4807fd9141 Mon Sep 17 00:00:00 2001 +From: Ryusuke Konishi +Date: Mon, 30 Jul 2012 14:42:07 -0700 +Subject: nilfs2: fix deadlock issue between chcp and thaw ioctls + +From: Ryusuke Konishi + +commit 572d8b3945a31bee7c40d21556803e4807fd9141 upstream. + +An fs-thaw ioctl causes deadlock with a chcp or mkcp -s command: + + chcp D ffff88013870f3d0 0 1325 1324 0x00000004 + ... + Call Trace: + nilfs_transaction_begin+0x11c/0x1a0 [nilfs2] + wake_up_bit+0x20/0x20 + copy_from_user+0x18/0x30 [nilfs2] + nilfs_ioctl_change_cpmode+0x7d/0xcf [nilfs2] + nilfs_ioctl+0x252/0x61a [nilfs2] + do_page_fault+0x311/0x34c + get_unmapped_area+0x132/0x14e + do_vfs_ioctl+0x44b/0x490 + __set_task_blocked+0x5a/0x61 + vm_mmap_pgoff+0x76/0x87 + __set_current_blocked+0x30/0x4a + sys_ioctl+0x4b/0x6f + system_call_fastpath+0x16/0x1b + thaw D ffff88013870d890 0 1352 1351 0x00000004 + ... + Call Trace: + rwsem_down_failed_common+0xdb/0x10f + call_rwsem_down_write_failed+0x13/0x20 + down_write+0x25/0x27 + thaw_super+0x13/0x9e + do_vfs_ioctl+0x1f5/0x490 + vm_mmap_pgoff+0x76/0x87 + sys_ioctl+0x4b/0x6f + filp_close+0x64/0x6c + system_call_fastpath+0x16/0x1b + +where the thaw ioctl deadlocked at thaw_super() when called while chcp was +waiting at nilfs_transaction_begin() called from +nilfs_ioctl_change_cpmode(). This deadlock is 100% reproducible. + +This is because nilfs_ioctl_change_cpmode() first locks sb->s_umount in +read mode and then waits for unfreezing in nilfs_transaction_begin(), +whereas thaw_super() locks sb->s_umount in write mode. The locking of +sb->s_umount here was intended to make snapshot mounts and the downgrade +of snapshots to checkpoints exclusive. + +This fixes the deadlock issue by replacing the sb->s_umount usage in +nilfs_ioctl_change_cpmode() with a dedicated mutex which protects snapshot +mounts. + +Signed-off-by: Ryusuke Konishi +Cc: Fernando Luis Vazquez Cao +Tested-by: Ryusuke Konishi +Signed-off-by: Andrew Morton +Signed-off-by: Linus Torvalds +Signed-off-by: Greg Kroah-Hartman + +--- + fs/nilfs2/ioctl.c | 4 ++-- + fs/nilfs2/super.c | 3 +++ + fs/nilfs2/the_nilfs.c | 1 + + fs/nilfs2/the_nilfs.h | 2 ++ + 4 files changed, 8 insertions(+), 2 deletions(-) + +--- a/fs/nilfs2/ioctl.c ++++ b/fs/nilfs2/ioctl.c +@@ -182,7 +182,7 @@ static int nilfs_ioctl_change_cpmode(str + if (copy_from_user(&cpmode, argp, sizeof(cpmode))) + goto out; + +- down_read(&inode->i_sb->s_umount); ++ mutex_lock(&nilfs->ns_snapshot_mount_mutex); + + nilfs_transaction_begin(inode->i_sb, &ti, 0); + ret = nilfs_cpfile_change_cpmode( +@@ -192,7 +192,7 @@ static int nilfs_ioctl_change_cpmode(str + else + nilfs_transaction_commit(inode->i_sb); /* never fails */ + +- up_read(&inode->i_sb->s_umount); ++ mutex_unlock(&nilfs->ns_snapshot_mount_mutex); + out: + mnt_drop_write(filp->f_path.mnt); + return ret; +--- a/fs/nilfs2/super.c ++++ b/fs/nilfs2/super.c +@@ -951,6 +951,8 @@ static int nilfs_attach_snapshot(struct + struct nilfs_root *root; + int ret; + ++ mutex_lock(&nilfs->ns_snapshot_mount_mutex); ++ + down_read(&nilfs->ns_segctor_sem); + ret = nilfs_cpfile_is_snapshot(nilfs->ns_cpfile, cno); + up_read(&nilfs->ns_segctor_sem); +@@ -975,6 +977,7 @@ static int nilfs_attach_snapshot(struct + ret = nilfs_get_root_dentry(s, root, root_dentry); + nilfs_put_root(root); + out: ++ mutex_unlock(&nilfs->ns_snapshot_mount_mutex); + return ret; + } + +--- a/fs/nilfs2/the_nilfs.c ++++ b/fs/nilfs2/the_nilfs.c +@@ -76,6 +76,7 @@ struct the_nilfs *alloc_nilfs(struct blo + nilfs->ns_bdev = bdev; + atomic_set(&nilfs->ns_ndirtyblks, 0); + init_rwsem(&nilfs->ns_sem); ++ mutex_init(&nilfs->ns_snapshot_mount_mutex); + INIT_LIST_HEAD(&nilfs->ns_dirty_files); + INIT_LIST_HEAD(&nilfs->ns_gc_inodes); + spin_lock_init(&nilfs->ns_inode_lock); +--- a/fs/nilfs2/the_nilfs.h ++++ b/fs/nilfs2/the_nilfs.h +@@ -47,6 +47,7 @@ enum { + * @ns_flags: flags + * @ns_bdev: block device + * @ns_sem: semaphore for shared states ++ * @ns_snapshot_mount_mutex: mutex to protect snapshot mounts + * @ns_sbh: buffer heads of on-disk super blocks + * @ns_sbp: pointers to super block data + * @ns_sbwtime: previous write time of super block +@@ -99,6 +100,7 @@ struct the_nilfs { + + struct block_device *ns_bdev; + struct rw_semaphore ns_sem; ++ struct mutex ns_snapshot_mount_mutex; + + /* + * used for diff --git a/queue-3.0/series b/queue-3.0/series index 814a7772c0f..5d40bdcb81b 100644 --- a/queue-3.0/series +++ b/queue-3.0/series @@ -1,2 +1,3 @@ redefine-atomic_init-and-atomic64_init-to-drop-the-casts.patch sunrpc-return-negative-value-in-case-rpcbind-client-creation-error.patch +nilfs2-fix-deadlock-issue-between-chcp-and-thaw-ioctls.patch