From: Miklos Szeredi <mszeredi@xxxxxxx>
Add a new inode operation which is called on regular file create. This is a
replacement for ->create() which allows the file to be opened atomically with
creation.
This function is also called for non-open creates (mknod(2)) with a NULL file
argument. Only one of ->create or ->atomic_create will be called, implementing
both makes no sense.
The functionality of this method partially overlaps that of ->atomic_open().
FUSE and 9P only use ->atomic_create, NFS, CIFS and CEPH use both.
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx>
---
fs/namei.c | 118 +++++++++++++++++++++++++++++++++++++++++-----------
include/linux/fs.h | 4 ++
2 files changed, 97 insertions(+), 25 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index 8dfbe45..200cffe 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1998,27 +1998,6 @@ void unlock_rename(struct dentry *p1, struct dentry *p2)
}
}
-int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
- struct nameidata *nd)
-{
- int error = may_create(dir, dentry);
-
- if (error)
- return error;
-
- if (!dir->i_op->create)
- return -EACCES; /* shouldn't it be ENOSYS? */
- mode &= S_IALLUGO;
- mode |= S_IFREG;
- error = security_inode_create(dir, dentry, mode);
- if (error)
- return error;
- error = dir->i_op->create(dir, dentry, mode, nd);
- if (!error)
- fsnotify_create(dir, dentry);
- return error;
-}
-
static int may_open(struct path *path, int acc_mode, int flag)
{
struct dentry *dentry = path->dentry;
@@ -2071,6 +2050,87 @@ static int may_open(struct path *path, int acc_mode, int flag)
return 0;
}
+static struct file *atomic_create(struct inode *dir, struct dentry *dentry,
+ struct opendata *od, unsigned open_flag,
+ umode_t mode)
+{
+ struct file *filp;
+ int error;
+
+ filp = dir->i_op->atomic_create(dir, dentry, od, open_flag, mode);
+ if (IS_ERR(filp))
+ goto out;
+
+ fsnotify_create(dir, dentry);
+
+ if (!filp)
+ goto out;
+
+ /*
+ * We don't have the inode before the open, so check open permission
+ * here.
+ */
+ error = may_open(&filp->f_path, MAY_OPEN, open_flag);
+ if (error)
+ goto out_fput;
+
+ error = open_check_o_direct(filp);
+ if (error)
+ goto out_fput;
+
+out:
+ return filp;
+
+out_fput:
+ fput(filp);
+ return ERR_PTR(error);
+}
+
+static struct file *create_open(struct inode *dir, struct dentry *dentry,
+ struct opendata *od, unsigned open_flag,
+ umode_t mode, struct nameidata *nd)
+{
+ int error = may_create(dir, dentry);
+ if (error)
+ goto out_err;
+
+ error = -EACCES; /* shouldn't it be ENOSYS? */
+ if (!dir->i_op->create && !dir->i_op->atomic_create)
+ goto out_err;
+ mode &= S_IALLUGO;
+ mode |= S_IFREG;
+ error = security_inode_create(dir, dentry, mode);
+ if (error)
+ goto out_err;
+ if (dir->i_op->create) {
+ error = dir->i_op->create(dir, dentry, mode, nd);
+ if (error)
+ goto out_err;
+
+ fsnotify_create(dir, dentry);
+ return NULL;
+ } else {
+ return atomic_create(dir, dentry, od, open_flag, mode);
+ }
+
+out_err:
+ return ERR_PTR(error);
+}
+
+int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
+ struct nameidata *nd)
+{
+ struct file *res;
+ unsigned open_flag = O_RDONLY|O_CREAT|O_EXCL;
+
+ res = create_open(dir, dentry, NULL, open_flag, mode, NULL);
+ if (IS_ERR(res))
+ return PTR_ERR(res);
+
+ BUG_ON(res != NULL);
+ return 0;
+}
+
static int handle_truncate(struct file *filp)
{
struct path *path = &filp->f_path;
@@ -2317,7 +2377,7 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
{
struct dentry *dir = nd->path.dentry;
struct dentry *dentry;
- int open_flag = op->open_flag;
+ int open_flag = open_to_namei_flags(op->open_flag);
int will_truncate = open_flag & O_TRUNC;
int want_write = 0;
int acc_mode = op->acc_mode;
@@ -2402,6 +2462,7 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
/* Negative dentry, create the file if O_CREAT */
if (!dentry->d_inode) {
+ struct opendata od;
umode_t mode = op->mode;
error = -ENOENT;
@@ -2430,12 +2491,19 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
error = security_path_mknod(&nd->path, dentry, mode, 0);
if (error)
goto exit_mutex_unlock;
- error = vfs_create(dir->d_inode, dentry, mode, nd);
- if (error)
- goto exit_mutex_unlock;
+ od.mnt = nd->path.mnt;
+ od.filp = &nd->intent.open.file;
+ filp = create_open(dir->d_inode, dentry, &od, open_flag, mode,
+ nd);
mutex_unlock(&dir->d_inode->i_mutex);
dput(nd->path.dentry);
nd->path.dentry = dentry;
+ if (filp) {
+ if (IS_ERR(filp))
+ goto out;
+
+ goto opened;
+ }
goto common;
}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 6615355..af291bb 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1659,6 +1659,10 @@ struct inode_operations {
struct file * (*atomic_open)(struct inode *, struct dentry *,
struct opendata *, unsigned open_flag,
umode_t create_mode, bool *created);
+ struct file * (*atomic_create)(struct inode *, struct dentry *,
+ struct opendata *, unsigned open_flag,
+ umode_t create_mode);
+
} ____cacheline_aligned;
struct seq_file;
--
1.7.7
--
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