Commit 9358c6d4 authored by Sage Weil's avatar Sage Weil

ceph: fix dentry rehashing on virtual .snap dir

If a lookup fails on the magic .snap directory, we bind it to a magic
snap directory inode in ceph_lookup_finish().  That code assumes the dentry
is unhashed, but a recent server-side change started returning NULL leases
on lookup failure, causing the .snap dentry to be hashed and NULL by
ceph_fill_trace().

This causes dentry hash chain corruption, or a dies when d_rehash()
includes
	BUG_ON(!d_unhashed(entry));

So, avoid processing the NULL dentry lease if it the dentry matches the
snapdir name in ceph_fill_trace().  That allows the lookup completion to
properly bind it to the snapdir inode.  BUG there if dentry is hashed to
be sure.
Signed-off-by: default avatarSage Weil <sage@newdream.net>
parent 2eaa9cfd
...@@ -488,6 +488,7 @@ struct dentry *ceph_finish_lookup(struct ceph_mds_request *req, ...@@ -488,6 +488,7 @@ struct dentry *ceph_finish_lookup(struct ceph_mds_request *req,
struct inode *inode = ceph_get_snapdir(parent); struct inode *inode = ceph_get_snapdir(parent);
dout("ENOENT on snapdir %p '%.*s', linking to snapdir %p\n", dout("ENOENT on snapdir %p '%.*s', linking to snapdir %p\n",
dentry, dentry->d_name.len, dentry->d_name.name, inode); dentry, dentry->d_name.len, dentry->d_name.name, inode);
BUG_ON(!d_unhashed(dentry));
d_add(dentry, inode); d_add(dentry, inode);
err = 0; err = 0;
} }
......
...@@ -886,6 +886,7 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req, ...@@ -886,6 +886,7 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req,
struct inode *in = NULL; struct inode *in = NULL;
struct ceph_mds_reply_inode *ininfo; struct ceph_mds_reply_inode *ininfo;
struct ceph_vino vino; struct ceph_vino vino;
struct ceph_client *client = ceph_sb_to_client(sb);
int i = 0; int i = 0;
int err = 0; int err = 0;
...@@ -949,7 +950,14 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req, ...@@ -949,7 +950,14 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req,
return err; return err;
} }
if (rinfo->head->is_dentry && !req->r_aborted) { /*
* ignore null lease/binding on snapdir ENOENT, or else we
* will have trouble splicing in the virtual snapdir later
*/
if (rinfo->head->is_dentry && !req->r_aborted &&
(rinfo->head->is_target || strncmp(req->r_dentry->d_name.name,
client->mount_args->snapdir_name,
req->r_dentry->d_name.len))) {
/* /*
* lookup link rename : null -> possibly existing inode * lookup link rename : null -> possibly existing inode
* mknod symlink mkdir : null -> new inode * mknod symlink mkdir : null -> new inode
......
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