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Subject[PATCH 4.18 150/197] btrfs: reorder initialization before the mount locks uuid_mutex
Date
4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Sterba <dsterba@suse.com>

[ Upstream commit 399f7f4c42e8a58c8456264d5112287aefe44cf4 ]

In preparation to take a big lock, move resource initialization before
the critical section. It's not obvious from the diff, the desired order
is:

- initialize mount security options
- allocate temporary fs_info
- allocate superblock buffers

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/btrfs/super.c | 30 ++++++++++++++----------------
1 file changed, 14 insertions(+), 16 deletions(-)

--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1528,14 +1528,6 @@ static struct dentry *btrfs_mount_root(s
if (!(flags & SB_RDONLY))
mode |= FMODE_WRITE;

- mutex_lock(&uuid_mutex);
- error = btrfs_parse_early_options(data, mode, fs_type,
- &fs_devices);
- mutex_unlock(&uuid_mutex);
- if (error) {
- return ERR_PTR(error);
- }
-
security_init_mnt_opts(&new_sec_opts);
if (data) {
error = parse_security_options(data, &new_sec_opts);
@@ -1543,12 +1535,6 @@ static struct dentry *btrfs_mount_root(s
return ERR_PTR(error);
}

- mutex_lock(&uuid_mutex);
- error = btrfs_scan_one_device(device_name, mode, fs_type, &fs_devices);
- mutex_unlock(&uuid_mutex);
- if (error)
- goto error_sec_opts;
-
/*
* Setup a dummy root and fs_info for test/set super. This is because
* we don't actually fill this stuff out until open_ctree, but we need
@@ -1561,8 +1547,6 @@ static struct dentry *btrfs_mount_root(s
goto error_sec_opts;
}

- fs_info->fs_devices = fs_devices;
-
fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_KERNEL);
fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_KERNEL);
security_init_mnt_opts(&fs_info->security_opts);
@@ -1572,6 +1556,20 @@ static struct dentry *btrfs_mount_root(s
}

mutex_lock(&uuid_mutex);
+ error = btrfs_parse_early_options(data, mode, fs_type, &fs_devices);
+ mutex_unlock(&uuid_mutex);
+ if (error)
+ goto error_fs_info;
+
+ mutex_lock(&uuid_mutex);
+ error = btrfs_scan_one_device(device_name, mode, fs_type, &fs_devices);
+ mutex_unlock(&uuid_mutex);
+ if (error)
+ goto error_fs_info;
+
+ fs_info->fs_devices = fs_devices;
+
+ mutex_lock(&uuid_mutex);
error = btrfs_open_devices(fs_devices, mode, fs_type);
mutex_unlock(&uuid_mutex);
if (error)

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