Commit a1147b82 authored by Trond Myklebust's avatar Trond Myklebust Committed by Anna Schumaker
Browse files

NFS: Fix up directory verifier races 



In order to avoid having our dentry revalidation race with an update
of the directory on the server, we need to store the verifier before
the RPC calls to LOOKUP and READDIR.

Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
Reviewed-by: default avatarBenjamin Coddington <bcodding@gmail.com>
Tested-by: default avatarBenjamin Coddington <bcodding@gmail.com>
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
parent bb6d3fb3

fs/nfs/dir.c

+14 −7
Original line number Diff line number Diff line
@@ -155,6 +155,7 @@ typedef struct { 
	loff_t		current_index;

	decode_dirent_t	decode;



	unsigned long	dir_verifier;

	unsigned long	timestamp;

	unsigned long	gencount;

	unsigned int	cache_entry_index;
@@ -353,6 +354,7 @@ int nfs_readdir_xdr_filler(struct page **pages, nfs_readdir_descriptor_t *desc, 
 again:

	timestamp = jiffies;

	gencount = nfs_inc_attr_generation_counter();

	desc->dir_verifier = nfs_save_change_attribute(inode);

	error = NFS_PROTO(inode)->readdir(file_dentry(file), cred, entry->cookie, pages,

					  NFS_SERVER(inode)->dtsize, desc->plus);

	if (error < 0) {
@@ -455,13 +457,13 @@ void nfs_force_use_readdirplus(struct inode *dir) 
}



static

void nfs_prime_dcache(struct dentry *parent, struct nfs_entry *entry)

void nfs_prime_dcache(struct dentry *parent, struct nfs_entry *entry,

		unsigned long dir_verifier)

{

	struct qstr filename = QSTR_INIT(entry->name, entry->len);

	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);

	struct dentry *dentry;

	struct dentry *alias;

	struct inode *dir = d_inode(parent);

	struct inode *inode;

	int status;
@@ -500,7 +502,7 @@ again: 
		if (nfs_same_file(dentry, entry)) {

			if (!entry->fh->size)

				goto out;

			nfs_set_verifier(dentry, nfs_save_change_attribute(dir));

			nfs_set_verifier(dentry, dir_verifier);

			status = nfs_refresh_inode(d_inode(dentry), entry->fattr);

			if (!status)

				nfs_setsecurity(d_inode(dentry), entry->fattr, entry->label);
@@ -526,7 +528,7 @@ again: 
		dput(dentry);

		dentry = alias;

	}

	nfs_set_verifier(dentry, nfs_save_change_attribute(dir));

	nfs_set_verifier(dentry, dir_verifier);

out:

	dput(dentry);

}
@@ -564,7 +566,8 @@ int nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct nfs_entry *en 
		count++;



		if (desc->plus)

			nfs_prime_dcache(file_dentry(desc->file), entry);

			nfs_prime_dcache(file_dentry(desc->file), entry,

					desc->dir_verifier);



		status = nfs_readdir_add_to_array(entry, page);

		if (status != 0)
@@ -1159,6 +1162,7 @@ nfs_lookup_revalidate_dentry(struct inode *dir, struct dentry *dentry, 
	struct nfs_fh *fhandle;

	struct nfs_fattr *fattr;

	struct nfs4_label *label;

	unsigned long dir_verifier;

	int ret;



	ret = -ENOMEM;
@@ -1168,6 +1172,7 @@ nfs_lookup_revalidate_dentry(struct inode *dir, struct dentry *dentry, 
	if (fhandle == NULL || fattr == NULL || IS_ERR(label))

		goto out;



	dir_verifier = nfs_save_change_attribute(dir);

	ret = NFS_PROTO(dir)->lookup(dir, dentry, fhandle, fattr, label);

	if (ret < 0) {

		switch (ret) {
@@ -1188,7 +1193,7 @@ nfs_lookup_revalidate_dentry(struct inode *dir, struct dentry *dentry, 
		goto out;



	nfs_setsecurity(inode, fattr, label);

	nfs_set_verifier(dentry, nfs_save_change_attribute(dir));

	nfs_set_verifier(dentry, dir_verifier);



	/* set a readdirplus hint that we had a cache miss */

	nfs_force_use_readdirplus(dir);
@@ -1415,6 +1420,7 @@ struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry, unsigned in 
	struct nfs_fh *fhandle = NULL;

	struct nfs_fattr *fattr = NULL;

	struct nfs4_label *label = NULL;

	unsigned long dir_verifier;

	int error;



	dfprintk(VFS, "NFS: lookup(%pd2)\n", dentry);
@@ -1440,6 +1446,7 @@ struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry, unsigned in 
	if (IS_ERR(label))

		goto out;



	dir_verifier = nfs_save_change_attribute(dir);

	trace_nfs_lookup_enter(dir, dentry, flags);

	error = NFS_PROTO(dir)->lookup(dir, dentry, fhandle, fattr, label);

	if (error == -ENOENT)
@@ -1463,7 +1470,7 @@ no_entry: 
			goto out_label;

		dentry = res;

	}

	nfs_set_verifier(dentry, nfs_save_change_attribute(dir));

	nfs_set_verifier(dentry, dir_verifier);

out_label:

	trace_nfs_lookup_exit(dir, dentry, flags, error);

	nfs4_label_free(label);

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