Skip to content

Commit

Permalink
NFS: Refactor nfs_lookup_revalidate()
Browse files Browse the repository at this point in the history 
Refactor the code in nfs_lookup_revalidate() as a stepping stone towards
optimising and fixing nfs4_lookup_revalidate().

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
  • Loading branch information
Trond Myklebust committed Sep 30, 2018
1 parent be189f7 commit 5ceb9d7
Showing 1 changed file with 126 additions and 96 deletions.
222 changes: 126 additions & 96 deletions fs/nfs/dir.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1072,6 +1072,100 @@ int nfs_neg_need_reval(struct inode *dir, struct dentry *dentry,
return !nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU);
}

static int
nfs_lookup_revalidate_done(struct inode *dir, struct dentry *dentry,
struct inode *inode, int error)
{
switch (error) {
case 1:
dfprintk(LOOKUPCACHE, "NFS: %s(%pd2) is valid\n",
__func__, dentry);
return 1;
case 0:
nfs_mark_for_revalidate(dir);
if (inode && S_ISDIR(inode->i_mode)) {
/* Purge readdir caches. */
nfs_zap_caches(inode);
/*
* We can't d_drop the root of a disconnected tree:
* its d_hash is on the s_anon list and d_drop() would hide
* it from shrink_dcache_for_unmount(), leading to busy
* inodes on unmount and further oopses.
*/
if (IS_ROOT(dentry))
return 1;
}
dfprintk(LOOKUPCACHE, "NFS: %s(%pd2) is invalid\n",
__func__, dentry);
return 0;
}
dfprintk(LOOKUPCACHE, "NFS: %s(%pd2) lookup returned error %d\n",
__func__, dentry, error);
return error;
}

static int
nfs_lookup_revalidate_negative(struct inode *dir, struct dentry *dentry,
unsigned int flags)
{
int ret = 1;
if (nfs_neg_need_reval(dir, dentry, flags)) {
if (flags & LOOKUP_RCU)
return -ECHILD;
ret = 0;
}
return nfs_lookup_revalidate_done(dir, dentry, NULL, ret);
}

static int
nfs_lookup_revalidate_delegated(struct inode *dir, struct dentry *dentry,
struct inode *inode)
{
nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
return nfs_lookup_revalidate_done(dir, dentry, inode, 1);
}

static int
nfs_lookup_revalidate_dentry(struct inode *dir, struct dentry *dentry,
struct inode *inode)
{
struct nfs_fh *fhandle;
struct nfs_fattr *fattr;
struct nfs4_label *label;
int ret;

ret = -ENOMEM;
fhandle = nfs_alloc_fhandle();
fattr = nfs_alloc_fattr();
label = nfs4_label_alloc(NFS_SERVER(inode), GFP_KERNEL);
if (fhandle == NULL || fattr == NULL || IS_ERR(label))
goto out;

ret = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, fhandle, fattr, label);
if (ret < 0) {
if (ret == -ESTALE || ret == -ENOENT)
ret = 0;
goto out;
}
ret = 0;
if (nfs_compare_fh(NFS_FH(inode), fhandle))
goto out;
if (nfs_refresh_inode(inode, fattr) < 0)
goto out;

nfs_setsecurity(inode, fattr, label);
nfs_set_verifier(dentry, nfs_save_change_attribute(dir));

/* set a readdirplus hint that we had a cache miss */
nfs_force_use_readdirplus(dir);
ret = 1;
out:
nfs_free_fattr(fattr);
nfs_free_fhandle(fhandle);
nfs4_label_free(label);
return nfs_lookup_revalidate_done(dir, dentry, inode, ret);
}

/*
* This is called every time the dcache has a lookup hit,
* and we should check whether we can really trust that
Expand All @@ -1083,58 +1177,36 @@ int nfs_neg_need_reval(struct inode *dir, struct dentry *dentry,
* If the parent directory is seen to have changed, we throw out the
* cached dentry and do a new lookup.
*/
static int nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
static int
nfs_do_lookup_revalidate(struct inode *dir, struct dentry *dentry,
unsigned int flags)
{
struct inode *dir;
struct inode *inode;
struct dentry *parent;
struct nfs_fh *fhandle = NULL;
struct nfs_fattr *fattr = NULL;
struct nfs4_label *label = NULL;
int error;

if (flags & LOOKUP_RCU) {
parent = READ_ONCE(dentry->d_parent);
dir = d_inode_rcu(parent);
if (!dir)
return -ECHILD;
} else {
parent = dget_parent(dentry);
dir = d_inode(parent);
}
nfs_inc_stats(dir, NFSIOS_DENTRYREVALIDATE);
inode = d_inode(dentry);

if (!inode) {
if (nfs_neg_need_reval(dir, dentry, flags)) {
if (flags & LOOKUP_RCU)
return -ECHILD;
goto out_bad;
}
goto out_valid;
}
if (!inode)
return nfs_lookup_revalidate_negative(dir, dentry, flags);

if (is_bad_inode(inode)) {
if (flags & LOOKUP_RCU)
return -ECHILD;
dfprintk(LOOKUPCACHE, "%s: %pd2 has dud inode\n",
__func__, dentry);
goto out_bad;
}

if (NFS_PROTO(dir)->have_delegation(inode, FMODE_READ))
goto out_set_verifier;
return nfs_lookup_revalidate_delegated(dir, dentry, inode);

/* Force a full look up iff the parent directory has changed */
if (!(flags & (LOOKUP_EXCL | LOOKUP_REVAL)) &&
nfs_check_verifier(dir, dentry, flags & LOOKUP_RCU)) {
error = nfs_lookup_verify_inode(inode, flags);
if (error) {
if (flags & LOOKUP_RCU)
return -ECHILD;
if (error == -ESTALE)
goto out_zap_parent;
goto out_error;
nfs_zap_caches(dir);
goto out_bad;
}
nfs_advise_use_readdirplus(dir);
goto out_valid;
Expand All @@ -1146,81 +1218,39 @@ static int nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
if (NFS_STALE(inode))
goto out_bad;

error = -ENOMEM;
fhandle = nfs_alloc_fhandle();
fattr = nfs_alloc_fattr();
if (fhandle == NULL || fattr == NULL)
goto out_error;

label = nfs4_label_alloc(NFS_SERVER(inode), GFP_NOWAIT);
if (IS_ERR(label))
goto out_error;

trace_nfs_lookup_revalidate_enter(dir, dentry, flags);
error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, fhandle, fattr, label);
error = nfs_lookup_revalidate_dentry(dir, dentry, inode);
trace_nfs_lookup_revalidate_exit(dir, dentry, flags, error);
if (error == -ESTALE || error == -ENOENT)
goto out_bad;
if (error)
goto out_error;
if (nfs_compare_fh(NFS_FH(inode), fhandle))
goto out_bad;
if ((error = nfs_refresh_inode(inode, fattr)) != 0)
goto out_bad;

nfs_setsecurity(inode, fattr, label);

nfs_free_fattr(fattr);
nfs_free_fhandle(fhandle);
nfs4_label_free(label);
return error;
out_valid:
return nfs_lookup_revalidate_done(dir, dentry, inode, 1);
out_bad:
if (flags & LOOKUP_RCU)
return -ECHILD;
return nfs_lookup_revalidate_done(dir, dentry, inode, 0);
}

/* set a readdirplus hint that we had a cache miss */
nfs_force_use_readdirplus(dir);
static int
nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
{
struct dentry *parent;
struct inode *dir;
int ret;

out_set_verifier:
nfs_set_verifier(dentry, nfs_save_change_attribute(dir));
out_valid:
if (flags & LOOKUP_RCU) {
parent = READ_ONCE(dentry->d_parent);
dir = d_inode_rcu(parent);
if (!dir)
return -ECHILD;
ret = nfs_do_lookup_revalidate(dir, dentry, flags);
if (parent != READ_ONCE(dentry->d_parent))
return -ECHILD;
} else
} else {
parent = dget_parent(dentry);
ret = nfs_do_lookup_revalidate(d_inode(parent), dentry, flags);
dput(parent);
dfprintk(LOOKUPCACHE, "NFS: %s(%pd2) is valid\n",
__func__, dentry);
return 1;
out_zap_parent:
nfs_zap_caches(dir);
out_bad:
WARN_ON(flags & LOOKUP_RCU);
nfs_free_fattr(fattr);
nfs_free_fhandle(fhandle);
nfs4_label_free(label);
nfs_mark_for_revalidate(dir);
if (inode && S_ISDIR(inode->i_mode)) {
/* Purge readdir caches. */
nfs_zap_caches(inode);
/*
* We can't d_drop the root of a disconnected tree:
* its d_hash is on the s_anon list and d_drop() would hide
* it from shrink_dcache_for_unmount(), leading to busy
* inodes on unmount and further oopses.
*/
if (IS_ROOT(dentry))
goto out_valid;
}
dput(parent);
dfprintk(LOOKUPCACHE, "NFS: %s(%pd2) is invalid\n",
__func__, dentry);
return 0;
out_error:
WARN_ON(flags & LOOKUP_RCU);
nfs_free_fattr(fattr);
nfs_free_fhandle(fhandle);
nfs4_label_free(label);
dput(parent);
dfprintk(LOOKUPCACHE, "NFS: %s(%pd2) lookup returned error %d\n",
__func__, dentry, error);
return error;
return ret;
}

/*
Expand Down

0 comments on commit 5ceb9d7

Please sign in to comment.