xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

nfsd4: fix delegation-unlink/rename race

Browse Source 
If a file is unlinked or renamed between the time when we do the local
open and the time when we get the delegation, then we will return to the
client indicating that it holds a delegation even though the file no
longer exists under the name it was open under.

But a client performing an open-by-name, when it is returned a
delegation, must be able to assume that the file is still linked at the
name it was opened under.

So, hold the parent i_mutex for longer to prevent concurrent renames or
unlinks.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
J. Bruce Fields
2014-01-24 18:04:40 -05:00
parent c0e6bee480
commit 4335723e8e
2 changed files with 13 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

7
fs/nfsd/vfs.c
View File

@@ -207,7 +207,12 @@ nfsd_lookup_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp,
goto out_nfserr;
}
} else {
fh_lock(fhp);
/*
* In the nfsd4_open() case, this may be held across
* subsequent open and delegation acquisition which may
* need to take the child's i_mutex:
*/
fh_lock_nested(fhp, I_MUTEX_PARENT);
dentry = lookup_one_len(name, dparent, len);
host_err = PTR_ERR(dentry);
if (IS_ERR(dentry))