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authorJosef Bacik <josef@redhat.com>2010-11-17 18:54:54 +0000
committerChris Mason <chris.mason@oracle.com>2010-11-21 22:26:08 -0500
commit2ede0daf01549cecf4bb0962c46dc47382047523 (patch)
tree3d02b4445b8657ac402a64772dd80ca517967557
parent0410c94aff109c02b6774a0ed00114987cda7ce5 (diff)
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Btrfs: handle NFS lookups properly
People kept reporting NFS issues, specifically getting ESTALE alot. I figured out how to reproduce the problem SERVER mkfs.btrfs /dev/sda1 mount /dev/sda1 /mnt/btrfs-test <add /mnt/btrfs-test to /etc/exports> btrfs subvol create /mnt/btrfs-test/foo service nfs start CLIENT mount server:/mnt/btrfs /mnt/test cd /mnt/test/foo ls SERVER echo 3 > /proc/sys/vm/drop_caches CLIENT ls <-- get an ESTALE here This is because the standard way to lookup a name in nfsd is to use readdir, and what it does is do a readdir on the parent directory looking for the inode of the child. So in this case the parent being / and the child being foo. Well subvols all have the same inode number, so doing a readdir of / looking for inode 256 will return '.', which obviously doesn't match foo. So instead we need to have our own .get_name so that we can find the right name. Our .get_name will either lookup the inode backref or the root backref, whichever we're looking for, and return the name we find. Running the above reproducer with this patch results in everything acting the way its supposed to. Thanks, Signed-off-by: Josef Bacik <josef@redhat.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
-rw-r--r--fs/btrfs/export.c76
1 files changed, 76 insertions, 0 deletions
diff --git a/fs/btrfs/export.c b/fs/btrfs/export.c
index 951ef09b82f..6f044447359 100644
--- a/fs/btrfs/export.c
+++ b/fs/btrfs/export.c
@@ -232,9 +232,85 @@ fail:
return ERR_PTR(ret);
}
+static int btrfs_get_name(struct dentry *parent, char *name,
+ struct dentry *child)
+{
+ struct inode *inode = child->d_inode;
+ struct inode *dir = parent->d_inode;
+ struct btrfs_path *path;
+ struct btrfs_root *root = BTRFS_I(dir)->root;
+ struct btrfs_inode_ref *iref;
+ struct btrfs_root_ref *rref;
+ struct extent_buffer *leaf;
+ unsigned long name_ptr;
+ struct btrfs_key key;
+ int name_len;
+ int ret;
+
+ if (!dir || !inode)
+ return -EINVAL;
+
+ if (!S_ISDIR(dir->i_mode))
+ return -EINVAL;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+ path->leave_spinning = 1;
+
+ if (inode->i_ino == BTRFS_FIRST_FREE_OBJECTID) {
+ key.objectid = BTRFS_I(inode)->root->root_key.objectid;
+ key.type = BTRFS_ROOT_BACKREF_KEY;
+ key.offset = (u64)-1;
+ root = root->fs_info->tree_root;
+ } else {
+ key.objectid = inode->i_ino;
+ key.offset = dir->i_ino;
+ key.type = BTRFS_INODE_REF_KEY;
+ }
+
+ ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+ if (ret < 0) {
+ btrfs_free_path(path);
+ return ret;
+ } else if (ret > 0) {
+ if (inode->i_ino == BTRFS_FIRST_FREE_OBJECTID) {
+ path->slots[0]--;
+ } else {
+ btrfs_free_path(path);
+ return -ENOENT;
+ }
+ }
+ leaf = path->nodes[0];
+
+ if (inode->i_ino == BTRFS_FIRST_FREE_OBJECTID) {
+ rref = btrfs_item_ptr(leaf, path->slots[0],
+ struct btrfs_root_ref);
+ name_ptr = (unsigned long)(rref + 1);
+ name_len = btrfs_root_ref_name_len(leaf, rref);
+ } else {
+ iref = btrfs_item_ptr(leaf, path->slots[0],
+ struct btrfs_inode_ref);
+ name_ptr = (unsigned long)(iref + 1);
+ name_len = btrfs_inode_ref_name_len(leaf, iref);
+ }
+
+ read_extent_buffer(leaf, name, name_ptr, name_len);
+ btrfs_free_path(path);
+
+ /*
+ * have to add the null termination to make sure that reconnect_path
+ * gets the right len for strlen
+ */
+ name[name_len] = '\0';
+
+ return 0;
+}
+
const struct export_operations btrfs_export_ops = {
.encode_fh = btrfs_encode_fh,
.fh_to_dentry = btrfs_fh_to_dentry,
.fh_to_parent = btrfs_fh_to_parent,
.get_parent = btrfs_get_parent,
+ .get_name = btrfs_get_name,
};