[PATCH 1/3] nfs: don't use ->d_time
From: Miklos Szeredi
Date: Mon Nov 07 2016 - 05:52:15 EST
NFS is the most complicated of the lot. It uses ->d_fsdata to
1) store devname in the root dentry, and
2) store nfs_unlinkdata for sillyrenames.
In addition it stores a verifier in ->d_time.
Introduce nfs_dentry structure that to store all of the above and make
d_fsdata point to it. Need to use rcu freeing since ->verf is accessed
from dentry revalidation. And not only read, but changed as well, so
rcu_head must not overlay verf.
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Cc: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
---
fs/nfs/dir.c | 18 ++++++++++++++----
fs/nfs/getroot.c | 4 ++--
fs/nfs/namespace.c | 2 +-
fs/nfs/unlink.c | 16 ++++++++--------
include/linux/nfs_fs.h | 19 ++++++++++++++++++-
5 files changed, 43 insertions(+), 16 deletions(-)
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 5f1af4cd1a33..5a3f02c4c28a 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1041,7 +1041,7 @@ static int nfs_check_verifier(struct inode *dir, struct dentry *dentry,
return 1;
if (NFS_SERVER(dir)->flags & NFS_MOUNT_LOOKUP_CACHE_NONE)
return 0;
- if (!nfs_verify_change_attribute(dir, dentry->d_time))
+ if (!nfs_verify_change_attribute(dir, NFS_D(dentry)->verf))
return 0;
/* Revalidate nfsi->cache_change_attribute before we declare a match */
if (rcu_walk)
@@ -1050,7 +1050,7 @@ static int nfs_check_verifier(struct inode *dir, struct dentry *dentry,
ret = nfs_revalidate_inode(NFS_SERVER(dir), dir);
if (ret < 0)
return 0;
- if (!nfs_verify_change_attribute(dir, dentry->d_time))
+ if (!nfs_verify_change_attribute(dir, NFS_D(dentry)->verf))
return 0;
return 1;
}
@@ -1358,15 +1358,23 @@ static void nfs_dentry_iput(struct dentry *dentry, struct inode *inode)
iput(inode);
}
+static int nfs_d_init(struct dentry *dentry)
+{
+ dentry->d_fsdata = kzalloc(sizeof(struct nfs_dentry), GFP_KERNEL);
+
+ return dentry->d_fsdata ? 0 : -ENOMEM;
+}
+
static void nfs_d_release(struct dentry *dentry)
{
/* free cached devname value, if it survived that far */
- if (unlikely(dentry->d_fsdata)) {
+ if (unlikely(NFS_D(dentry)->devname)) {
if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
WARN_ON(1);
else
- kfree(dentry->d_fsdata);
+ kfree(NFS_D(dentry)->devname);
}
+ kfree_rcu(NFS_D(dentry), rcu);
}
const struct dentry_operations nfs_dentry_operations = {
@@ -1375,6 +1383,7 @@ const struct dentry_operations nfs_dentry_operations = {
.d_delete = nfs_dentry_delete,
.d_iput = nfs_dentry_iput,
.d_automount = nfs_d_automount,
+ .d_init = nfs_d_init,
.d_release = nfs_d_release,
};
EXPORT_SYMBOL_GPL(nfs_dentry_operations);
@@ -1453,6 +1462,7 @@ const struct dentry_operations nfs4_dentry_operations = {
.d_delete = nfs_dentry_delete,
.d_iput = nfs_dentry_iput,
.d_automount = nfs_d_automount,
+ .d_init = nfs_d_init,
.d_release = nfs_d_release,
};
EXPORT_SYMBOL_GPL(nfs4_dentry_operations);
diff --git a/fs/nfs/getroot.c b/fs/nfs/getroot.c
index a608ffd28acc..84482c656e05 100644
--- a/fs/nfs/getroot.c
+++ b/fs/nfs/getroot.c
@@ -120,9 +120,9 @@ struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh *mntfh,
security_d_instantiate(ret, inode);
spin_lock(&ret->d_lock);
- if (IS_ROOT(ret) && !ret->d_fsdata &&
+ if (IS_ROOT(ret) && !NFS_D(ret)->devname &&
!(ret->d_flags & DCACHE_NFSFS_RENAMED)) {
- ret->d_fsdata = name;
+ NFS_D(ret)->devname = name;
name = NULL;
}
spin_unlock(&ret->d_lock);
diff --git a/fs/nfs/namespace.c b/fs/nfs/namespace.c
index c8162c660c44..0060806d047b 100644
--- a/fs/nfs/namespace.c
+++ b/fs/nfs/namespace.c
@@ -90,7 +90,7 @@ char *nfs_path(char **p, struct dentry *dentry, char *buffer, ssize_t buflen,
*--end = '/';
}
*p = end;
- base = dentry->d_fsdata;
+ base = NFS_D(dentry)->devname;
if (!base) {
spin_unlock(&dentry->d_lock);
rcu_read_unlock();
diff --git a/fs/nfs/unlink.c b/fs/nfs/unlink.c
index 191aa577dd1f..74e708fbd945 100644
--- a/fs/nfs/unlink.c
+++ b/fs/nfs/unlink.c
@@ -134,8 +134,8 @@ static int nfs_call_unlink(struct dentry *dentry, struct nfs_unlinkdata *data)
spin_lock(&alias->d_lock);
if (d_really_is_positive(alias) &&
!(alias->d_flags & DCACHE_NFSFS_RENAMED)) {
- devname_garbage = alias->d_fsdata;
- alias->d_fsdata = data;
+ devname_garbage = NFS_D(alias)->devname;
+ NFS_D(alias)->data = data;
alias->d_flags |= DCACHE_NFSFS_RENAMED;
ret = 1;
} else
@@ -189,8 +189,8 @@ nfs_async_unlink(struct dentry *dentry, const struct qstr *name)
if (dentry->d_flags & DCACHE_NFSFS_RENAMED)
goto out_unlock;
dentry->d_flags |= DCACHE_NFSFS_RENAMED;
- devname_garbage = dentry->d_fsdata;
- dentry->d_fsdata = data;
+ devname_garbage = NFS_D(dentry)->devname;
+ NFS_D(dentry)->data = data;
spin_unlock(&dentry->d_lock);
/*
* If we'd displaced old cached devname, free it. At that
@@ -226,8 +226,8 @@ nfs_complete_unlink(struct dentry *dentry, struct inode *inode)
spin_lock(&dentry->d_lock);
dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
- data = dentry->d_fsdata;
- dentry->d_fsdata = NULL;
+ data = NFS_D(dentry)->data;
+ NFS_D(dentry)->data = NULL;
spin_unlock(&dentry->d_lock);
if (NFS_STALE(inode) || !nfs_call_unlink(dentry, data))
@@ -240,10 +240,10 @@ nfs_cancel_async_unlink(struct dentry *dentry)
{
spin_lock(&dentry->d_lock);
if (dentry->d_flags & DCACHE_NFSFS_RENAMED) {
- struct nfs_unlinkdata *data = dentry->d_fsdata;
+ struct nfs_unlinkdata *data = NFS_D(dentry)->data;
dentry->d_flags &= ~DCACHE_NFSFS_RENAMED;
- dentry->d_fsdata = NULL;
+ NFS_D(dentry)->data = NULL;
spin_unlock(&dentry->d_lock);
nfs_free_unlinkdata(data);
return;
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 810124b33327..20a07688a392 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -187,6 +187,18 @@ struct nfs_inode {
};
/*
+ * NFS specific dentry data
+ */
+struct nfs_dentry {
+ union {
+ char *devname;
+ struct nfs_unlinkdata *data;
+ struct rcu_head rcu;
+ };
+ unsigned long verf;
+};
+
+/*
* Cache validity bit flags
*/
#define NFS_INO_INVALID_ATTR 0x0001 /* cached attrs are invalid */
@@ -217,6 +229,11 @@ static inline struct nfs_inode *NFS_I(const struct inode *inode)
return container_of(inode, struct nfs_inode, vfs_inode);
}
+static inline struct nfs_dentry *NFS_D(struct dentry *dentry)
+{
+ return (struct nfs_dentry *) dentry->d_fsdata;
+}
+
static inline struct nfs_server *NFS_SB(const struct super_block *s)
{
return (struct nfs_server *)(s->s_fs_info);
@@ -299,7 +316,7 @@ static inline int nfs_server_capable(struct inode *inode, int cap)
static inline void nfs_set_verifier(struct dentry * dentry, unsigned long verf)
{
- dentry->d_time = verf;
+ NFS_D(dentry)->verf = verf;
}
/**
--
2.5.5