From 7f9f05e1f4cd9a625bc35b117a239d9b0cbe4a03 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Fri, 19 Nov 2010 14:59:15 -0500 Subject: [PATCH 3/3] Btrfs: setup blank root and fs_info for mount time There is a problem with how we use sget, it searches through the list of supers attached to the fs_type looking for a super with the same fs_devices as what we're trying to mount. This depends on sb->s_fs_info being filled, but we don't fill that in until we get to btrfs_fill_super, so we could hit supers on the fs_type super list that have a null s_fs_info. In order to fix that we need to go ahead and setup a blank root with a blank fs_info to hold fs_devices, that way our test will work out right and then we can set s_fs_info in btrfs_set_super, and then open_ctree will simply use our pre-allocated root and fs_info when setting everything up. Thanks, Signed-off-by: Josef Bacik Signed-off-by: Chris Mason --- fs/btrfs/disk-io.c | 6 ++---- fs/btrfs/super.c | 34 +++++++++++++++++++++++++++++++--- 2 files changed, 33 insertions(+), 7 deletions(-) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 64f1008..65efa04 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1539,10 +1539,8 @@ struct btrfs_root *open_ctree(struct super_block *sb, GFP_NOFS); struct btrfs_root *csum_root = kzalloc(sizeof(struct btrfs_root), GFP_NOFS); - struct btrfs_root *tree_root = kzalloc(sizeof(struct btrfs_root), - GFP_NOFS); - struct btrfs_fs_info *fs_info = kzalloc(sizeof(*fs_info), - GFP_NOFS); + struct btrfs_root *tree_root = btrfs_sb(sb); + struct btrfs_fs_info *fs_info = tree_root->fs_info; struct btrfs_root *chunk_root = kzalloc(sizeof(struct btrfs_root), GFP_NOFS); struct btrfs_root *dev_root = kzalloc(sizeof(struct btrfs_root), diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index b169698..6479db9 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -548,7 +548,7 @@ static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs) static int btrfs_test_super(struct super_block *s, void *data) { - struct btrfs_fs_devices *test_fs_devices = data; + struct btrfs_root *test_root = data; struct btrfs_root *root = btrfs_sb(s); /* @@ -557,9 +557,17 @@ static int btrfs_test_super(struct super_block *s, void *data) */ if (!atomic_read(&s->s_active)) return 0; - return root->fs_info->fs_devices == test_fs_devices; + return root->fs_info->fs_devices == test_root->fs_info->fs_devices; } +static int btrfs_set_super(struct super_block *s, void *data) +{ + s->s_fs_info = data; + + return set_anon_super(s, data); +} + + /* * Find a superblock for the given device / mount point. * @@ -573,6 +581,8 @@ static int btrfs_get_sb(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; u64 subvol_objectid = 0; @@ -601,8 +611,24 @@ static int btrfs_get_sb(struct file_system_type *fs_type, int flags, 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 + * it for searching for existing supers, so this lets us do that and + * then open_ctree will properly initialize everything later. + */ + fs_info = kzalloc(sizeof(struct btrfs_fs_info), GFP_NOFS); + tree_root = kzalloc(sizeof(struct btrfs_root), GFP_NOFS); + if (!fs_info || !tree_root) { + error = -ENOMEM; + goto error_close_devices; + } + fs_info->tree_root = tree_root; + fs_info->fs_devices = fs_devices; + tree_root->fs_info = fs_info; + bdev = fs_devices->latest_bdev; - s = sget(fs_type, btrfs_test_super, set_anon_super, fs_devices); + s = sget(fs_type, btrfs_test_super, btrfs_set_super, tree_root); if (IS_ERR(s)) goto error_s; @@ -672,6 +698,8 @@ error_s: error = PTR_ERR(s); error_close_devices: btrfs_close_devices(fs_devices); + kfree(fs_info); + kfree(tree_root); error_free_subvol_name: kfree(subvol_name); return error; -- 1.7.3.3