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Btrfs: rework error handling in btrfs_mount()

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Commits 6c41761f and 45ea6095 introduced the possibility of NULL pointer
dereference on error paths, also we would leave all devices busy and
leak fs_info with all sub-structures on error when trying to mount an
already mounted fs to a different directory.

Fix this by doing all allocations before trying to open any of the
devices, adjust error path for mount-already-mounted-fs case.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
This commit is contained in:
Ilya Dryomov 2011-11-09 14:41:22 +02:00
parent 586e46e281
commit 04d21a244f
1 changed files with 21 additions and 21 deletions
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42
fs/btrfs/super.c
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@ -891,7 +891,6 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
struct super_block *s;
struct dentry *root;
struct btrfs_fs_devices *fs_devices = NULL;
struct btrfs_root *tree_root = NULL;
struct btrfs_fs_info *fs_info = NULL;
fmode_t mode = FMODE_READ;
char *subvol_name = NULL;
@ -920,15 +919,6 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
if (error)
return ERR_PTR(error);
error = btrfs_open_devices(fs_devices, mode, fs_type);
if (error)
return ERR_PTR(error);
if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
error = -EACCES;
goto error_close_devices;
}
/*
* 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
@ -936,28 +926,36 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
* then open_ctree will properly initialize everything later.
*/
fs_info = kzalloc(sizeof(struct btrfs_fs_info), GFP_NOFS);
if (!fs_info) {
if (!fs_info)
return ERR_PTR(-ENOMEM);
fs_info->tree_root = kzalloc(sizeof(struct btrfs_root), GFP_NOFS);
if (!fs_info->tree_root) {
error = -ENOMEM;
goto error_close_devices;
goto error_fs_info;
}
tree_root = kzalloc(sizeof(struct btrfs_root), GFP_NOFS);
if (!tree_root) {
error = -ENOMEM;
goto error_close_devices;
}
fs_info->tree_root = tree_root;
fs_info->tree_root->fs_info = fs_info;
fs_info->fs_devices = fs_devices;
tree_root->fs_info = fs_info;
fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
if (!fs_info->super_copy || !fs_info->super_for_commit) {
error = -ENOMEM;
goto error_fs_info;
}
error = btrfs_open_devices(fs_devices, mode, fs_type);
if (error)
goto error_fs_info;
if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
error = -EACCES;
goto error_close_devices;
}
bdev = fs_devices->latest_bdev;
s = sget(fs_type, btrfs_test_super, btrfs_set_super, tree_root);
s = sget(fs_type, btrfs_test_super, btrfs_set_super,
fs_info->tree_root);
if (IS_ERR(s)) {
error = PTR_ERR(s);
goto error_close_devices;
@ -966,7 +964,8 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
if (s->s_root) {
if ((flags ^ s->s_flags) & MS_RDONLY) {
deactivate_locked_super(s);
return ERR_PTR(-EBUSY);
error = -EBUSY;
goto error_close_devices;
}
btrfs_close_devices(fs_devices);
@ -997,6 +996,7 @@ static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
error_close_devices:
btrfs_close_devices(fs_devices);
error_fs_info:
free_fs_info(fs_info);
return ERR_PTR(error);
}