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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 <josef@redhat.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
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parent
975f84fee2
commit
450ba0ea06
@ -1561,10 +1561,8 @@ struct btrfs_root *open_ctree(struct super_block *sb,
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GFP_NOFS);
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struct btrfs_root *csum_root = kzalloc(sizeof(struct btrfs_root),
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GFP_NOFS);
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struct btrfs_root *tree_root = kzalloc(sizeof(struct btrfs_root),
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GFP_NOFS);
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struct btrfs_fs_info *fs_info = kzalloc(sizeof(*fs_info),
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GFP_NOFS);
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struct btrfs_root *tree_root = btrfs_sb(sb);
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struct btrfs_fs_info *fs_info = tree_root->fs_info;
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struct btrfs_root *chunk_root = kzalloc(sizeof(struct btrfs_root),
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GFP_NOFS);
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struct btrfs_root *dev_root = kzalloc(sizeof(struct btrfs_root),
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@ -563,7 +563,7 @@ static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
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static int btrfs_test_super(struct super_block *s, void *data)
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{
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struct btrfs_fs_devices *test_fs_devices = data;
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struct btrfs_root *test_root = data;
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struct btrfs_root *root = btrfs_sb(s);
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/*
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@ -572,9 +572,17 @@ static int btrfs_test_super(struct super_block *s, void *data)
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*/
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if (!atomic_read(&s->s_active))
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return 0;
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return root->fs_info->fs_devices == test_fs_devices;
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return root->fs_info->fs_devices == test_root->fs_info->fs_devices;
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}
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static int btrfs_set_super(struct super_block *s, void *data)
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{
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s->s_fs_info = data;
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return set_anon_super(s, data);
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}
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/*
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* Find a superblock for the given device / mount point.
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*
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@ -588,6 +596,8 @@ static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
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struct super_block *s;
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struct dentry *root;
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struct btrfs_fs_devices *fs_devices = NULL;
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struct btrfs_root *tree_root = NULL;
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struct btrfs_fs_info *fs_info = NULL;
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fmode_t mode = FMODE_READ;
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char *subvol_name = NULL;
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u64 subvol_objectid = 0;
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@ -615,8 +625,24 @@ static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
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goto error_close_devices;
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}
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/*
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* Setup a dummy root and fs_info for test/set super. This is because
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* we don't actually fill this stuff out until open_ctree, but we need
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* it for searching for existing supers, so this lets us do that and
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* then open_ctree will properly initialize everything later.
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*/
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fs_info = kzalloc(sizeof(struct btrfs_fs_info), GFP_NOFS);
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tree_root = kzalloc(sizeof(struct btrfs_root), GFP_NOFS);
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if (!fs_info || !tree_root) {
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error = -ENOMEM;
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goto error_close_devices;
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}
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fs_info->tree_root = tree_root;
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fs_info->fs_devices = fs_devices;
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tree_root->fs_info = fs_info;
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bdev = fs_devices->latest_bdev;
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s = sget(fs_type, btrfs_test_super, set_anon_super, fs_devices);
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s = sget(fs_type, btrfs_test_super, btrfs_set_super, tree_root);
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if (IS_ERR(s))
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goto error_s;
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@ -685,6 +711,8 @@ error_s:
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error = PTR_ERR(s);
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error_close_devices:
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btrfs_close_devices(fs_devices);
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kfree(fs_info);
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kfree(tree_root);
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error_free_subvol_name:
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kfree(subvol_name);
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return error;
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