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ceph: don't return -ESTALE if there's still an open file 

Similarly to commit 03f219041f ("ceph: check i_nlink while converting
a file handle to dentry"), this fixes another corner case with
name_to_handle_at/open_by_handle_at.  The issue has been detected by
xfstest generic/467, when doing:

 - name_to_handle_at("/cephfs/myfile")
 - open("/cephfs/myfile")
 - unlink("/cephfs/myfile")
 - sync; sync;
 - drop caches
 - open_by_handle_at()

The call to open_by_handle_at should not fail because the file hasn't been
deleted yet (only unlinked) and we do have a valid handle to it.  -ESTALE
shall be returned only if i_nlink is 0 *and* i_count is 1.

This patch also makes sure we have LINK caps before checking i_nlink.

Signed-off-by: Luis Henriques <lhenriques@suse.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
This commit is contained in:
Luis Henriques 2020-05-18 18:47:26 +01:00 committed by Ilya Dryomov
parent 53ab8e7cd2
commit 878dabb641
1 changed files with 8 additions and 1 deletions
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9
fs/ceph/export.c
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@ -172,9 +172,16 @@ struct inode *ceph_lookup_inode(struct super_block *sb, u64 ino)
static struct dentry *__fh_to_dentry(struct super_block *sb, u64 ino) static struct dentry *__fh_to_dentry(struct super_block *sb, u64 ino)
{ {
struct inode *inode = __lookup_inode(sb, ino); struct inode *inode = __lookup_inode(sb, ino);
int err;
if (IS_ERR(inode)) if (IS_ERR(inode))
return ERR_CAST(inode); return ERR_CAST(inode);
if (inode->i_nlink == 0) { /* We need LINK caps to reliably check i_nlink */
err = ceph_do_getattr(inode, CEPH_CAP_LINK_SHARED, false);
if (err)
return ERR_PTR(err);
/* -ESTALE if inode as been unlinked and no file is open */
if ((inode->i_nlink == 0) && (atomic_read(&inode->i_count) == 1)) {
iput(inode); iput(inode);
return ERR_PTR(-ESTALE); return ERR_PTR(-ESTALE);
} }