* [PATCH] cleanup read/write
@ 2002-05-15 14:38 Christoph Hellwig
0 siblings, 0 replies; only message in thread
From: Christoph Hellwig @ 2002-05-15 14:38 UTC (permalink / raw)
To: Linus Torvalds, Marcelo Tosatti; +Cc: linux-kernel
Currently sys_read/sys_pread and sys_write/sys_pwrite basically contain
lots of duplication of the same checks/code.
The patch below moves all that into vfs_read/vfs_write helpers that have
the same prototypes as the read/write file operations. In addition I
have choosen to export these interfaces to module so people doing inkernel
file reading/writing can use these instead of duplicating the checks
(which is very likely to be done wrong).
The patch applies against 2.4 and 2.5 without changes.
--- linux-2.4.19-pre8-ac3/fs/read_write.c Fri May 3 13:38:32 2002
+++ linux/fs/read_write.c Wed May 15 17:19:47 2002
@@ -144,57 +144,107 @@
}
#endif
-asmlinkage ssize_t sys_read(unsigned int fd, char * buf, size_t count)
+ssize_t vfs_read(struct file *file, char *buf, size_t count, loff_t *pos)
{
+ struct inode *inode = file->f_dentry->d_inode;
ssize_t ret;
- struct file * file;
- ret = -EBADF;
- file = fget(fd);
- if (file) {
- if (file->f_mode & FMODE_READ) {
- ret = locks_verify_area(FLOCK_VERIFY_READ, file->f_dentry->d_inode,
- file, file->f_pos, count);
- if (!ret) {
- ssize_t (*read)(struct file *, char *, size_t, loff_t *);
- ret = -EINVAL;
- if (file->f_op && (read = file->f_op->read) != NULL)
- ret = read(file, buf, count, &file->f_pos);
- }
- }
+ if (!(file->f_mode & FMODE_READ))
+ return -EBADF;
+ if (!file->f_op || !file->f_op->read)
+ return -EINVAL;
+ if (pos < 0)
+ return -EINVAL;
+
+ ret = locks_verify_area(FLOCK_VERIFY_READ, inode, file, *pos, count);
+ if (!ret) {
+ ret = file->f_op->read(file, buf, count, pos);
if (ret > 0)
dnotify_parent(file->f_dentry, DN_ACCESS);
+ }
+
+ return ret;
+}
+
+ssize_t vfs_write(struct file *file, const char *buf, size_t count, loff_t *pos)
+{
+ struct inode *inode = file->f_dentry->d_inode;
+ ssize_t ret;
+
+ if (!(file->f_mode & FMODE_WRITE))
+ return -EBADF;
+ if (!file->f_op || !file->f_op->write)
+ return -EINVAL;
+ if (pos < 0)
+ return -EINVAL;
+
+ ret = locks_verify_area(FLOCK_VERIFY_WRITE, inode, file, *pos, count);
+ if (!ret) {
+ ret = file->f_op->write(file, buf, count, pos);
+ if (ret > 0)
+ dnotify_parent(file->f_dentry, DN_MODIFY);
+ }
+
+ return ret;
+}
+
+asmlinkage ssize_t sys_read(unsigned int fd, char * buf, size_t count)
+{
+ struct file *file;
+ ssize_t ret = -EBADF;
+
+ file = fget(fd);
+ if (file) {
+ ret = vfs_read(file, buf, count, &file->f_pos);
fput(file);
}
+
return ret;
}
asmlinkage ssize_t sys_write(unsigned int fd, const char * buf, size_t count)
{
- ssize_t ret;
- struct file * file;
+ struct file *file;
+ ssize_t ret = -EBADF;
- ret = -EBADF;
file = fget(fd);
if (file) {
- if (file->f_mode & FMODE_WRITE) {
- struct inode *inode = file->f_dentry->d_inode;
- ret = locks_verify_area(FLOCK_VERIFY_WRITE, inode, file,
- file->f_pos, count);
- if (!ret) {
- ssize_t (*write)(struct file *, const char *, size_t, loff_t *);
- ret = -EINVAL;
- if (file->f_op && (write = file->f_op->write) != NULL)
- ret = write(file, buf, count, &file->f_pos);
- }
- }
- if (ret > 0)
- dnotify_parent(file->f_dentry, DN_MODIFY);
+ ret = vfs_write(file, buf, count, &file->f_pos);
fput(file);
}
+
return ret;
}
+asmlinkage ssize_t sys_pread(unsigned int fd, char *buf,
+ size_t count, loff_t pos)
+{
+ struct file *file;
+ ssize_t ret = -EBADF;
+
+ file = fget(fd);
+ if (file) {
+ ret = vfs_read(file, buf, count, &pos);
+ fput(file);
+ }
+
+ return ret;
+}
+
+asmlinkage ssize_t sys_pwrite(unsigned int fd, const char *buf,
+ size_t count, loff_t pos)
+{
+ struct file *file;
+ ssize_t ret = -EBADF;
+
+ file = fget(fd);
+ if (file) {
+ ret = vfs_write(file, buf, count, &pos);
+ fput(file);
+ }
+
+ return ret;
+}
static ssize_t do_readv_writev(int type, struct file *file,
const struct iovec * vector,
@@ -337,70 +387,3 @@
bad_file:
return ret;
}
-
-/* From the Single Unix Spec: pread & pwrite act like lseek to pos + op +
- lseek back to original location. They fail just like lseek does on
- non-seekable files. */
-
-asmlinkage ssize_t sys_pread(unsigned int fd, char * buf,
- size_t count, loff_t pos)
-{
- ssize_t ret;
- struct file * file;
- ssize_t (*read)(struct file *, char *, size_t, loff_t *);
-
- ret = -EBADF;
- file = fget(fd);
- if (!file)
- goto bad_file;
- if (!(file->f_mode & FMODE_READ))
- goto out;
- ret = locks_verify_area(FLOCK_VERIFY_READ, file->f_dentry->d_inode,
- file, pos, count);
- if (ret)
- goto out;
- ret = -EINVAL;
- if (!file->f_op || !(read = file->f_op->read))
- goto out;
- if (pos < 0)
- goto out;
- ret = read(file, buf, count, &pos);
- if (ret > 0)
- dnotify_parent(file->f_dentry, DN_ACCESS);
-out:
- fput(file);
-bad_file:
- return ret;
-}
-
-asmlinkage ssize_t sys_pwrite(unsigned int fd, const char * buf,
- size_t count, loff_t pos)
-{
- ssize_t ret;
- struct file * file;
- ssize_t (*write)(struct file *, const char *, size_t, loff_t *);
-
- ret = -EBADF;
- file = fget(fd);
- if (!file)
- goto bad_file;
- if (!(file->f_mode & FMODE_WRITE))
- goto out;
- ret = locks_verify_area(FLOCK_VERIFY_WRITE, file->f_dentry->d_inode,
- file, pos, count);
- if (ret)
- goto out;
- ret = -EINVAL;
- if (!file->f_op || !(write = file->f_op->write))
- goto out;
- if (pos < 0)
- goto out;
-
- ret = write(file, buf, count, &pos);
- if (ret > 0)
- dnotify_parent(file->f_dentry, DN_MODIFY);
-out:
- fput(file);
-bad_file:
- return ret;
-}
--- linux-2.4.19-pre8-ac3/kernel/ksyms.c Tue May 14 16:52:11 2002
+++ linux/kernel/ksyms.c Wed May 15 17:31:10 2002
@@ -242,6 +242,8 @@
EXPORT_SYMBOL(find_inode_number);
EXPORT_SYMBOL(is_subdir);
EXPORT_SYMBOL(get_unused_fd);
+EXPORT_SYMBOL(vfs_read);
+EXPORT_SYMBOL(vfs_write);
EXPORT_SYMBOL(vfs_create);
EXPORT_SYMBOL(vfs_mkdir);
EXPORT_SYMBOL(vfs_mknod);
--- linux-2.4.19-pre8-ac3/include/linux/fs.h Tue May 14 16:52:10 2002
+++ linux/include/linux/fs.h Wed May 15 17:27:52 2002
@@ -821,6 +821,9 @@
extern int vfs_unlink(struct inode *, struct dentry *);
extern int vfs_rename(struct inode *, struct dentry *, struct inode *, struct dentry *);
+extern ssize_t vfs_read(struct file *, char *, size_t, loff_t *);
+extern ssize_t vfs_write(struct file *, const char *, size_t, loff_t *);
+
/*
* File types
*/
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