commit 4fa2c54b5198d09607a534e2fd436581064587ed
NFS: nfs4_do_open should add negative results to the dcache.
used "d_drop(); d_add();" to ensure that a dentry was hashed
as a negative cached entry.
This is not safe if the dentry has an non-NULL ->d_inode.
It will trigger a BUG_ON in d_instantiate().
In that case, d_delete() is needed.
Also, only d_add if the dentry is currently unhashed, it seems
pointless removed and re-adding it unchanged.
Reported-by: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Fixes: 4fa2c54b5198d09607a534e2fd436581064587ed
Cc: Jeff Layton <jeff.layton@xxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20140908144525.GB19811@xxxxxxxxxxxxx
Signed-off-by: NeilBrown <neilb@xxxxxxx>
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 7dd8aca31c29..ac2dd953fc18 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2226,9 +2226,13 @@ static int _nfs4_open_and_get_state(struct nfs4_opendata *opendata,
ret = _nfs4_proc_open(opendata);
if (ret != 0) {
if (ret == -ENOENT) {
- d_drop(opendata->dentry);
- d_add(opendata->dentry, NULL);
- nfs_set_verifier(opendata->dentry,
+ dentry = opendata->dentry;
+ if (dentry->d_inode)
+ d_delete(dentry);
+ else if (d_unhashed(dentry))
+ d_add(dentry, NULL);
+
+ nfs_set_verifier(dentry,
nfs_save_change_attribute(opendata->dir->d_inode));
}
goto out;
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