Commit 7775ec57 authored by Jeff Layton's avatar Jeff Layton Committed by J. Bruce Fields
Browse files

nfsd: close cached files prior to a REMOVE or RENAME that would replace target 



It's not uncommon for some workloads to do a bunch of I/O to a file and
delete it just afterward. If knfsd has a cached open file however, then
the file may still be open when the dentry is unlinked. If the
underlying filesystem is nfs, then that could trigger it to do a
sillyrename.

On a REMOVE or RENAME scan the nfsd_file cache for open files that
correspond to the inode, and proactively unhash and put their
references. This should prevent any delete-on-last-close activity from
occurring, solely due to knfsd's open file cache.

This must be done synchronously though so we use the variants that call
flush_delayed_fput. There are deadlock possibilities if you call
flush_delayed_fput while holding locks, however. In the case of
nfsd_rename, we don't even do the lookups of the dentries to be renamed
until we've locked for rename.

Once we've figured out what the target dentry is for a rename, check to
see whether there are cached open files associated with it. If there
are, then unwind all of the locking, close them all, and then reattempt
the rename.

Signed-off-by: default avatarJeff Layton <jeff.layton@primarydata.com>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent 501cb184

fs/nfsd/vfs.c

+53 −9
Original line number Diff line number Diff line
@@ -1590,6 +1590,26 @@ out_nfserr: 
	goto out_unlock;

}



static void

nfsd_close_cached_files(struct dentry *dentry)

{

	struct inode *inode = d_inode(dentry);



	if (inode && S_ISREG(inode->i_mode))

		nfsd_file_close_inode_sync(inode);

}



static bool

nfsd_has_cached_files(struct dentry *dentry)

{

	bool		ret = false;

	struct inode *inode = d_inode(dentry);



	if (inode && S_ISREG(inode->i_mode))

		ret = nfsd_file_is_cached(inode);

	return ret;

}



/*

 * Rename a file

 * N.B. After this call _both_ ffhp and tfhp need an fh_put
@@ -1602,6 +1622,7 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen, 
	struct inode	*fdir, *tdir;

	__be32		err;

	int		host_err;

	bool		has_cached = false;



	err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_REMOVE);

	if (err)
@@ -1620,6 +1641,7 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen, 
	if (!flen || isdotent(fname, flen) || !tlen || isdotent(tname, tlen))

		goto out;



retry:

	host_err = fh_want_write(ffhp);

	if (host_err) {

		err = nfserrno(host_err);
@@ -1659,12 +1681,17 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen, 
	if (ffhp->fh_export->ex_path.dentry != tfhp->fh_export->ex_path.dentry)

		goto out_dput_new;



	if (nfsd_has_cached_files(ndentry)) {

		has_cached = true;

		goto out_dput_old;

	} else {

		host_err = vfs_rename(fdir, odentry, tdir, ndentry, NULL, 0);

		if (!host_err) {

			host_err = commit_metadata(tfhp);

			if (!host_err)

				host_err = commit_metadata(ffhp);

		}

	}

 out_dput_new:

	dput(ndentry);

 out_dput_old:
@@ -1676,12 +1703,26 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen, 
	 * as that would do the wrong thing if the two directories

	 * were the same, so again we do it by hand.

	 */

	if (!has_cached) {

		fill_post_wcc(ffhp);

		fill_post_wcc(tfhp);

	}

	unlock_rename(tdentry, fdentry);

	ffhp->fh_locked = tfhp->fh_locked = false;

	fh_drop_write(ffhp);



	/*

	 * If the target dentry has cached open files, then we need to try to

	 * close them prior to doing the rename. Flushing delayed fput

	 * shouldn't be done with locks held however, so we delay it until this

	 * point and then reattempt the whole shebang.

	 */

	if (has_cached) {

		has_cached = false;

		nfsd_close_cached_files(ndentry);

		dput(ndentry);

		goto retry;

	}

out:

	return err;

}
@@ -1728,10 +1769,13 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, 
	if (!type)

		type = d_inode(rdentry)->i_mode & S_IFMT;



	if (type != S_IFDIR)

	if (type != S_IFDIR) {

		nfsd_close_cached_files(rdentry);

		host_err = vfs_unlink(dirp, rdentry, NULL);

	else

	} else {

		host_err = vfs_rmdir(dirp, rdentry);

	}



	if (!host_err)

		host_err = commit_metadata(fhp);

	dput(rdentry);

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