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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: Sage Weil <sage@newdream.net>
This commit is contained in:
Sage Weil 2010-03-30 13:54:41 -07:00
parent 2eaa9cfdf3
commit 9358c6d4c0
2 changed files with 10 additions and 1 deletions
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1
fs/ceph/dir.c
View File

@ -488,6 +488,7 @@ struct dentry *ceph_finish_lookup(struct ceph_mds_request *req,
struct inode *inode = ceph_get_snapdir(parent);
dout("ENOENT on snapdir %p '%.*s', linking to snapdir %p\n",
dentry, dentry->d_name.len, dentry->d_name.name, inode);
BUG_ON(!d_unhashed(dentry));
d_add(dentry, inode);
err = 0;
}

10
fs/ceph/inode.c
View File

@ -886,6 +886,7 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req,
struct inode *in = NULL;
struct ceph_mds_reply_inode *ininfo;
struct ceph_vino vino;
struct ceph_client *client = ceph_sb_to_client(sb);
int i = 0;
int err = 0;
@ -949,7 +950,14 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req,
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
* mknod symlink mkdir : null -> new inode