Add pread/pwrite support bits to match the lseek bit.

This also removes the ESPIPE logic from pipes and seq_files,
since the VFS layer now supports it. 

arch/mips/kernel/linux32.c

@@ -477,6 +477,9 @@ asmlinkage ssize_t sys32_pread(unsigned int fd, char * buf,
 		goto out;
 	if (pos < 0)
 		goto out;
+	ret = -ESPIPE;
+	if (!(file->f_mode & FMODE_PREAD))
+		goto out;
 	ret = read(file, buf, count, &pos);
 	if (ret > 0)
 		dnotify_parent(file->f_dentry, DN_ACCESS);
@@ -511,6 +514,10 @@ asmlinkage ssize_t sys32_pwrite(unsigned int fd, const char * buf,
 	if (pos < 0)
 		goto out;
 
+	ret = -ESPIPE;
+	if (!(file->f_mode & FMODE_PWRITE))
+		goto out;
+
 	ret = write(file, buf, count, &pos);
 	if (ret > 0)
 		dnotify_parent(file->f_dentry, DN_MODIFY);

fs/fifo.c

@@ -44,7 +44,9 @@ static int fifo_open(struct inode *inode, struct file *filp)
 			goto err_nocleanup;
 	}
 	filp->f_version = 0;
-	filp->f_mode &= ~FMODE_LSEEK;
+
+	/* We can only do regular read/write on fifos */
+	filp->f_mode &= (FMODE_READ | FMODE_WRITE);
 
 	switch (filp->f_mode) {
 	case 1:

fs/file_table.c

@@ -117,7 +117,7 @@ int open_private_file(struct file *filp, struct dentry *dentry, int flags)
 	memset(filp, 0, sizeof(*filp));
 	eventpoll_init_file(filp);
 	filp->f_flags  = flags;
-	filp->f_mode   = ((flags+1) & O_ACCMODE) | FMODE_LSEEK;
+	filp->f_mode   = ((flags+1) & O_ACCMODE) | FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
 	atomic_set(&filp->f_count, 1);
 	filp->f_dentry = dentry;
 	filp->f_mapping = dentry->d_inode->i_mapping;

fs/nfsd/nfs4state.c

@@ -1140,10 +1140,9 @@ int status;
 
 	if (share_access & NFS4_SHARE_ACCESS_WRITE) {
 		status = get_write_access(filp->f_dentry->d_inode);
-		if (!status)
-			filp->f_mode = FMODE_WRITE | FMODE_LSEEK;
-		else
+		if (status)
 			return nfserrno(status);
+		filp->f_mode = (filp->f_mode | FMODE_WRITE) & ~FMODE_READ;
 	}
 	return nfs_ok;
 }
@@ -1153,7 +1152,7 @@ nfs4_file_downgrade(struct file *filp, unsigned int share_access)
 {
 	if (share_access & NFS4_SHARE_ACCESS_WRITE) {
 		put_write_access(filp->f_dentry->d_inode);
-		filp->f_mode = FMODE_READ | FMODE_LSEEK;
+		filp->f_mode = (filp->f_mode | FMODE_READ) & ~FMODE_WRITE;
 	}
 }
 

fs/open.c

@@ -781,7 +781,7 @@ struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
 	if (!f)
 		goto cleanup_dentry;
 	f->f_flags = flags;
-	f->f_mode = ((flags+1) & O_ACCMODE) | FMODE_LSEEK;
+	f->f_mode = ((flags+1) & O_ACCMODE) | FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
 	inode = dentry->d_inode;
 	if (f->f_mode & FMODE_WRITE) {
 		error = get_write_access(inode);

fs/pipe.c

@@ -94,10 +94,6 @@ pipe_readv(struct file *filp, const struct iovec *_iov,
 	struct iovec *iov = (struct iovec *)_iov;
 	size_t total_len;
 
-	/* pread is not allowed on pipes. */
-	if (unlikely(ppos != &filp->f_pos))
-		return -ESPIPE;
-
 	total_len = iov_length(iov, nr_segs);
 	/* Null read succeeds. */
 	if (unlikely(total_len == 0))
@@ -187,10 +183,6 @@ pipe_writev(struct file *filp, const struct iovec *_iov,
 	struct iovec *iov = (struct iovec *)_iov;
 	size_t total_len;
 
-	/* pwrite is not allowed on pipes. */
-	if (unlikely(ppos != &filp->f_pos))
-		return -ESPIPE;
-
 	total_len = iov_length(iov, nr_segs);
 	/* Null write succeeds. */
 	if (unlikely(total_len == 0))

fs/read_write.c

@@ -314,7 +314,7 @@ asmlinkage ssize_t sys_pread64(unsigned int fd, char __user *buf,
 	file = fget_light(fd, &fput_needed);
 	if (file) {
 		ret = -ESPIPE;
-		if (file->f_mode & FMODE_LSEEK)
+		if (file->f_mode & FMODE_PREAD)
 			ret = vfs_read(file, buf, count, &pos);
 		fput_light(file, fput_needed);
 	}
@@ -335,7 +335,7 @@ asmlinkage ssize_t sys_pwrite64(unsigned int fd, const char __user *buf,
 	file = fget_light(fd, &fput_needed);
 	if (file) {
 		ret = -ESPIPE;
-		if (file->f_mode & FMODE_LSEEK)  
+		if (file->f_mode & FMODE_PWRITE)  
 			ret = vfs_write(file, buf, count, &pos);
 		fput_light(file, fput_needed);
 	}

fs/seq_file.c

@@ -35,6 +35,9 @@ int seq_open(struct file *file, struct seq_operations *op)
 	sema_init(&p->sem, 1);
 	p->op = op;
 	file->private_data = p;
+
+	/* SEQ files support lseek, but not pread/pwrite */
+	file->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
 	return 0;
 }
 EXPORT_SYMBOL(seq_open);
@@ -54,9 +57,6 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
 	void *p;
 	int err = 0;
 
-	if (ppos != &file->f_pos)
-		return -EPIPE;
-
 	down(&m->sem);
 	/* grab buffer if we didn't have one */
 	if (!m->buf) {

include/linux/fs.h

@@ -74,7 +74,11 @@ extern int leases_enable, dir_notify_enable, lease_break_time;
 
 #define FMODE_READ 1
 #define FMODE_WRITE 2
-#define FMODE_LSEEK 4	/* Internal kernel extension */
+
+/* Internal kernel extensions */
+#define FMODE_LSEEK	4
+#define FMODE_PREAD	8
+#define FMODE_PWRITE	FMODE_PREAD	/* These go hand in hand */
 
 #define RW_MASK		1
 #define RWA_MASK	2