85 lines
2.4 KiB
Diff
85 lines
2.4 KiB
Diff
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From: Li Zefan <lizf@cn.fujitsu.com>
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Date: Wed, 7 Dec 2011 13:13:26 +0800
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Patch-mainline: pending
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References: FATE#306586
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Subject: [PATCH] Btrfs: fix possible deadlock when opening a seed device
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The correct lock order is uuid_mutex -> volume_mutex -> chunk_mutex,
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but when we mount a filesystem which has backing seed devices, we have
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this lock chain:
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open_ctree()
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lock(chunk_mutex);
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read_chunk_tree();
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read_one_dev();
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open_seed_devices();
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lock(uuid_mutex);
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and then we hit a lockdep splat.
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Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
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Signed-off-by: David Sterba <dsterba@suse.cz>
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---
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fs/btrfs/disk-io.c | 2 --
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fs/btrfs/volumes.c | 9 +++++++--
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2 files changed, 7 insertions(+), 4 deletions(-)
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diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
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index d0bc3c5..beb1d19 100644
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--- a/fs/btrfs/disk-io.c
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+++ b/fs/btrfs/disk-io.c
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@@ -2287,9 +2287,7 @@ struct btrfs_root *open_ctree(struct super_block *sb,
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(unsigned long)btrfs_header_chunk_tree_uuid(chunk_root->node),
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BTRFS_UUID_SIZE);
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- mutex_lock(&fs_info->chunk_mutex);
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ret = btrfs_read_chunk_tree(chunk_root);
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- mutex_unlock(&fs_info->chunk_mutex);
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if (ret) {
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printk(KERN_WARNING "btrfs: failed to read chunk tree on %s\n",
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sb->s_id);
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diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
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index d136915..fc94228 100644
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--- a/fs/btrfs/volumes.c
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+++ b/fs/btrfs/volumes.c
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@@ -4264,7 +4264,7 @@ static int open_seed_devices(struct btrfs_root *root, u8 *fsid)
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struct btrfs_fs_devices *fs_devices;
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int ret;
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- mutex_lock(&uuid_mutex);
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+ BUG_ON(!mutex_is_locked(&uuid_mutex));
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fs_devices = root->fs_info->fs_devices->seed;
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while (fs_devices) {
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@@ -4302,7 +4302,6 @@ static int open_seed_devices(struct btrfs_root *root, u8 *fsid)
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fs_devices->seed = root->fs_info->fs_devices->seed;
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root->fs_info->fs_devices->seed = fs_devices;
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out:
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- mutex_unlock(&uuid_mutex);
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return ret;
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}
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@@ -4459,6 +4458,9 @@ int btrfs_read_chunk_tree(struct btrfs_root *root)
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if (!path)
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return -ENOMEM;
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+ mutex_lock(&uuid_mutex);
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+ lock_chunks(root);
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+
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/* first we search for all of the device items, and then we
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* read in all of the chunk items. This way we can create chunk
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* mappings that reference all of the devices that are afound
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@@ -4509,6 +4511,9 @@ again:
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}
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ret = 0;
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error:
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+ unlock_chunks(root);
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+ mutex_unlock(&uuid_mutex);
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+
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btrfs_free_path(path);
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return ret;
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}
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--
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1.7.6.233.gd79bc
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