[PATCH] 2.5.4-pre1: further llseek cleanup (1/3)

This is the first of three patches implementing further llseek cleanup,
against 2.5.4-pre1.

The 'push locking into llseek methods' patch was integrated into 2.5.3.
The networking filesystems, however, do not protect i_size and can not
rely on the inode semaphore used in generic_file_llseek.

This patch implements a remote_llseek method, which is basically the
pre-2.5.3 version of generic_file_llseek.  Locking is done via the BKL.
When we have a saner locking system in place, we can push it into this
function in lieu.

Ncpfs, nfs, and smbfs have been converted to use this new llseek.

Note this is updated over the previous posted patch.

	Robert Love

6 files changed, 30 insertions, 3 deletions

diff --git a/fs/ncpfs/file.c b/fs/ncpfs/file.c
index 1f70ec451ce7..fbd2c3137dd4 100644
--- a/fs/ncpfs/file.c
+++ b/fs/ncpfs/file.c
@@ -281,7 +281,7 @@ static int ncp_release(struct inode *inode, struct file *file) {
 
 struct file_operations ncp_file_operations =
 {
-	llseek:		generic_file_llseek,
+	llseek:		remote_llseek,
 	read:		ncp_file_read,
 	write:		ncp_file_write,
 	ioctl:		ncp_ioctl,
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 1d5e7dbde28a..d25cb4968931 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -41,7 +41,7 @@ static int  nfs_file_flush(struct file *);
 static int  nfs_fsync(struct file *, struct dentry *dentry, int datasync);
 
 struct file_operations nfs_file_operations = {
-	llseek:		generic_file_llseek,
+	llseek:		remote_llseek,
 	read:		nfs_file_read,
 	write:		nfs_file_write,
 	mmap:		nfs_file_mmap,
diff --git a/fs/read_write.c b/fs/read_write.c
index 31cee2a6aa4e..ce5230669579 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -51,6 +51,31 @@ loff_t generic_file_llseek(struct file *file, loff_t offset, int origin)
 	return retval;
 }
 
+loff_t remote_llseek(struct file *file, loff_t offset, int origin)
+{
+	long long retval;
+
+	lock_kernel();
+	switch (origin) {
+		case 2:
+			offset += file->f_dentry->d_inode->i_size;
+			break;
+		case 1:
+			offset += file->f_pos;
+	}
+	retval = -EINVAL;
+	if (offset>=0 && offset<=file->f_dentry->d_inode->i_sb->s_maxbytes) {
+		if (offset != file->f_pos) {
+			file->f_pos = offset;
+			file->f_reada = 0;
+			file->f_version = ++event;
+		}
+		retval = offset;
+	}
+	unlock_kernel();
+	return retval;
+}
+
 loff_t no_llseek(struct file *file, loff_t offset, int origin)
 {
 	return -ESPIPE;
diff --git a/fs/smbfs/file.c b/fs/smbfs/file.c
index b3feaa56924a..39badd71692f 100644
--- a/fs/smbfs/file.c
+++ b/fs/smbfs/file.c
@@ -381,7 +381,7 @@ smb_file_permission(struct inode *inode, int mask)
 
 struct file_operations smb_file_operations =
 {
-	llseek:		generic_file_llseek,
+	llseek:		remote_llseek,
 	read:		smb_file_read,
 	write:		smb_file_write,
 	ioctl:		smb_ioctl,
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 461566f52c16..f4699a15157d 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1461,6 +1461,7 @@ extern ssize_t generic_file_write(struct file *, const char *, size_t, loff_t *)
 extern void do_generic_file_read(struct file *, loff_t *, read_descriptor_t *, read_actor_t);
 extern loff_t no_llseek(struct file *file, loff_t offset, int origin);
 extern loff_t generic_file_llseek(struct file *file, loff_t offset, int origin);
+extern loff_t remote_llseek(struct file *file, loff_t offset, int origin);
 extern ssize_t generic_read_dir(struct file *, char *, size_t, loff_t *);
 extern int generic_file_open(struct inode * inode, struct file * filp);
 
diff --git a/kernel/ksyms.c b/kernel/ksyms.c
index c271a8e6f6fc..73db2a0b2678 100644
--- a/kernel/ksyms.c
+++ b/kernel/ksyms.c
@@ -251,6 +251,7 @@ EXPORT_SYMBOL(vfs_rename);
 EXPORT_SYMBOL(vfs_statfs);
 EXPORT_SYMBOL(generic_read_dir);
 EXPORT_SYMBOL(generic_file_llseek);
+EXPORT_SYMBOL(remote_llseek);
 EXPORT_SYMBOL(no_llseek);
 EXPORT_SYMBOL(__pollwait);
 EXPORT_SYMBOL(poll_freewait);