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Subject[PATCH] 2.5: further llseek cleanup (1/3)
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Linus,

This is the first of three patches implementing further llseek cleanup,
against 2.5.3.

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.

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

As always, Al's blessing is desired, but since he helped me on this I
think he concurs ;-)

Robert Love

diff -urN linux-2.5.3/fs/coda/file.c linux/fs/coda/file.c
--- linux-2.5.3/fs/coda/file.c Thu Jan 31 01:08:54 2002
+++ linux/fs/coda/file.c Thu Jan 31 01:09:47 2002
@@ -267,7 +267,7 @@
}

struct file_operations coda_file_operations = {
- llseek: generic_file_llseek,
+ llseek: remote_llseek,
read: coda_file_read,
write: coda_file_write,
mmap: coda_file_mmap,
diff -urN linux-2.5.3/fs/ncpfs/file.c linux/fs/ncpfs/file.c
--- linux-2.5.3/fs/ncpfs/file.c Thu Jan 31 01:08:54 2002
+++ linux/fs/ncpfs/file.c Thu Jan 31 01:09:47 2002
@@ -281,7 +281,7 @@

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 -urN linux-2.5.3/fs/nfs/file.c linux/fs/nfs/file.c
--- linux-2.5.3/fs/nfs/file.c Thu Jan 31 01:08:54 2002
+++ linux/fs/nfs/file.c Thu Jan 31 01:09:47 2002
@@ -41,7 +41,7 @@
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 -urN linux-2.5.3/fs/read_write.c linux/fs/read_write.c
--- linux-2.5.3/fs/read_write.c Thu Jan 31 01:08:54 2002
+++ linux/fs/read_write.c Thu Jan 31 01:12:09 2002
@@ -51,6 +51,31 @@
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 -urN linux-2.5.3/fs/smbfs/file.c linux/fs/smbfs/file.c
--- linux-2.5.3/fs/smbfs/file.c Thu Jan 31 01:08:54 2002
+++ linux/fs/smbfs/file.c Thu Jan 31 01:09:47 2002
@@ -381,7 +381,7 @@

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 -urN linux-2.5.3/include/linux/fs.h linux/include/linux/fs.h
--- linux-2.5.3/include/linux/fs.h Thu Jan 31 01:08:54 2002
+++ linux/include/linux/fs.h Thu Jan 31 01:10:37 2002
@@ -1449,6 +1449,7 @@
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 -urN linux-2.5.3/kernel/ksyms.c linux/kernel/ksyms.c
--- linux-2.5.3/kernel/ksyms.c Thu Jan 31 01:08:54 2002
+++ linux/kernel/ksyms.c Thu Jan 31 01:10:06 2002
@@ -251,6 +251,7 @@
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);
-
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