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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: Trond Myklebust <trond.myklebust@hammerspace.com>
Reviewed-by: Benjamin Coddington <bcodding@gmail.com>
Tested-by: Benjamin Coddington <bcodding@gmail.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Trond Myklebust 2020-02-05 09:01:52 -05:00 committed by Anna Schumaker
parent bb6d3fb354
commit a1147b8281
1 changed files with 14 additions and 7 deletions
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21
fs/nfs/dir.c
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@ -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);