From: Miklos Szeredi <mszeredi@xxxxxxx>
NFS optimizes away the last component lookup for exclusive creation (create,
mkdir, mknod, link, symlink). It does this by checking for LOOKUP_EXCL in
nd->flags and skipping the actual lookup in that case, leaving a negative
unhashed dentry for the create function to fill.
Move this logic into the VFS which can be enabled by a filesystem flag.
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx>
---
fs/namei.c | 12 +++++++++++-
fs/nfs/dir.c | 22 ++++++++++++----------
fs/nfs/super.c | 9 ++++++---
include/linux/fs.h | 1 +
4 files changed, 30 insertions(+), 14 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index 5c95ce5..3e3652c 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2709,6 +2709,7 @@ struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir)
{
+ bool need_lookup;
struct dentry *dentry = ERR_PTR(-EEXIST);
struct nameidata nd;
int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd);
@@ -2728,10 +2729,19 @@ struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path
* Do the final lookup.
*/
mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
- dentry = lookup_hash(&nd);
+ dentry = lookup_dcache(&nd.last, nd.path.dentry, &nd, &need_lookup);
if (IS_ERR(dentry))
goto fail;
+ if (need_lookup) {
+ struct inode *dir = nd.path.dentry->d_inode;
+ if (!(dir->i_sb->s_type->fs_flags & FS_SKIP_LOOKUP_EXCL)) {
+ dentry = lookup_real(dir, dentry, &nd);
+ if (IS_ERR(dentry))
+ goto fail;
+ }
+ }
+
if (dentry->d_inode)
goto eexist;
/*
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 887226d..2b91cf3 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1286,16 +1286,6 @@ static struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry, stru
if (dentry->d_name.len > NFS_SERVER(dir)->namelen)
goto out;
- /*
- * If we're doing an exclusive create, optimize away the lookup
- * but don't hash the dentry.
- */
- if (nfs_is_exclusive_create(dir, nd)) {
- d_instantiate(dentry, NULL);
- res = NULL;
- goto out;
- }
-
res = ERR_PTR(-ENOMEM);
fhandle = nfs_alloc_fhandle();
fattr = nfs_alloc_fattr();
@@ -1612,6 +1602,9 @@ nfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t rdev)
dfprintk(VFS, "NFS: mknod(%s/%ld), %s\n",
dir->i_sb->s_id, dir->i_ino, dentry->d_name.name);
+ if (dentry->d_name.len > NFS_SERVER(dir)->namelen)
+ return -ENAMETOOLONG;
+
if (!new_valid_dev(rdev))
return -EINVAL;
@@ -1638,6 +1631,9 @@ static int nfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
dfprintk(VFS, "NFS: mkdir(%s/%ld), %s\n",
dir->i_sb->s_id, dir->i_ino, dentry->d_name.name);
+ if (dentry->d_name.len > NFS_SERVER(dir)->namelen)
+ return -ENAMETOOLONG;
+
attr.ia_valid = ATTR_MODE;
attr.ia_mode = mode | S_IFDIR;
@@ -1771,6 +1767,9 @@ static int nfs_symlink(struct inode *dir, struct dentry *dentry, const char *sym
dfprintk(VFS, "NFS: symlink(%s/%ld, %s, %s)\n", dir->i_sb->s_id,
dir->i_ino, dentry->d_name.name, symname);
+ if (dentry->d_name.len > NFS_SERVER(dir)->namelen)
+ return -ENAMETOOLONG;
+
if (pathlen > PAGE_SIZE)
return -ENAMETOOLONG;
@@ -1824,6 +1823,9 @@ nfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
old_dentry->d_parent->d_name.name, old_dentry->d_name.name,
dentry->d_parent->d_name.name, dentry->d_name.name);
+ if (dentry->d_name.len > NFS_SERVER(dir)->namelen)
+ return -ENAMETOOLONG;
+
nfs_inode_return_delegation(inode);
d_drop(dentry);
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 3dfa4f1..41ec94b 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -279,7 +279,8 @@ static struct file_system_type nfs_fs_type = {
.name = "nfs",
.mount = nfs_fs_mount,
.kill_sb = nfs_kill_super,
- .fs_flags = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
+ .fs_flags = FS_RENAME_DOES_D_MOVE | FS_REVAL_DOT |
+ FS_BINARY_MOUNTDATA | FS_SKIP_LOOKUP_EXCL,
};
struct file_system_type nfs_xdev_fs_type = {
@@ -287,7 +288,8 @@ struct file_system_type nfs_xdev_fs_type = {
.name = "nfs",
.mount = nfs_xdev_mount,
.kill_sb = nfs_kill_super,
- .fs_flags = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
+ .fs_flags = FS_RENAME_DOES_D_MOVE | FS_REVAL_DOT |
+ FS_BINARY_MOUNTDATA | FS_SKIP_LOOKUP_EXCL,
};
static const struct super_operations nfs_sops = {
@@ -327,7 +329,8 @@ static struct file_system_type nfs4_fs_type = {
.name = "nfs4",
.mount = nfs4_mount,
.kill_sb = nfs4_kill_super,
- .fs_flags = FS_RENAME_DOES_D_MOVE|FS_REVAL_DOT|FS_BINARY_MOUNTDATA,
+ .fs_flags = FS_RENAME_DOES_D_MOVE | FS_REVAL_DOT |
+ FS_BINARY_MOUNTDATA | FS_SKIP_LOOKUP_EXCL,
};
static struct file_system_type nfs4_remote_fs_type = {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index ea9282d..4a5e0d3 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -183,6 +183,7 @@ struct inodes_stat_t {
*/
#define FS_NO_LOOKUP_OPEN 0x10000 /* fs can't do atomic lookup+open */
#define FS_NO_LOOKUP_CREATE 0x20000 /* fs can't do lookup+create+open */
+#define FS_SKIP_LOOKUP_EXCL 0x40000 /* skip lookup for exclusive create */
/*
* These are the fs-independent mount-flags: up to 32 flags are supported
--
1.7.7
--
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