Hi,
As part of my buffer head cleanup attempt, I added "nobh" support
for ext3 writeback mode. I am still doing testing, so its not ready
for mainline.
How to use it ?
mount -o data=writeback,nobh <bdev> <mntpoint>
I really don't like the way I handled ext3_block_truncate_page()
for "nobh" support. Better ideas ? calling ->prepare_write()
to update the page doesn't seem to work due to journaling violations.
BTW, this patch depends on my earlier patch which adds
"nobh_writepage()" (currently in 2.6.11-rc4-mm1).
Thanks,
Badari
Signed-off-by: Badari Pulavarty <[EMAIL PROTECTED]>
diff -Narup -Xdontdiff linux-2.6.10.org/fs/ext3/inode.c
linux-2.6.10.nobh/fs/ext3/inode.c
--- linux-2.6.10.org/fs/ext3/inode.c 2004-12-24 13:35:01.000000000 -0800
+++ linux-2.6.10.nobh/fs/ext3/inode.c 2005-02-25 11:25:50.497488248 -0800
@@ -20,6 +20,7 @@
* ([EMAIL PROTECTED])
*
* Assorted race fixes, rewrite of ext3_get_block() by Al Viro, 2000
+ * Added "nobh" support to ext3 writeback mode - [EMAIL PROTECTED]
*/
#include <linux/module.h>
@@ -1008,7 +1009,11 @@ retry:
ret = PTR_ERR(handle);
goto out;
}
- ret = block_prepare_write(page, from, to, ext3_get_block);
+ if (ext3_should_writeback_data(inode) &&
+ test_opt(inode->i_sb, NOBH))
+ ret = nobh_prepare_write(page, from, to, ext3_get_block);
+ else
+ ret = block_prepare_write(page, from, to, ext3_get_block);
if (ret)
goto prepare_write_failed;
@@ -1092,7 +1097,12 @@ static int ext3_writeback_commit_write(s
new_i_size = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
if (new_i_size > EXT3_I(inode)->i_disksize)
EXT3_I(inode)->i_disksize = new_i_size;
- ret = generic_commit_write(file, page, from, to);
+
+ if (test_opt(inode->i_sb, NOBH))
+ ret = nobh_commit_write(file, page, from, to);
+ else
+ ret = generic_commit_write(file, page, from, to);
+
ret2 = ext3_journal_stop(handle);
if (!ret)
ret = ret2;
@@ -1338,7 +1348,11 @@ static int ext3_writeback_writepage(stru
goto out_fail;
}
- ret = block_write_full_page(page, ext3_get_block, wbc);
+ if (test_opt(inode->i_sb, NOBH))
+ ret = nobh_writepage(page, ext3_get_block, wbc);
+ else
+ ret = block_write_full_page(page, ext3_get_block, wbc);
+
err = ext3_journal_stop(handle);
if (!ret)
ret = err;
@@ -1598,13 +1612,34 @@ static int ext3_block_truncate_page(hand
unsigned blocksize, iblock, length, pos;
struct inode *inode = mapping->host;
struct buffer_head *bh;
- int err;
+ int err = 0;
void *kaddr;
blocksize = inode->i_sb->s_blocksize;
length = blocksize - (offset & (blocksize - 1));
iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
+ if (ext3_should_writeback_data(inode) && test_opt(inode->i_sb, NOBH)) {
+ if (!PageUptodate(page)) {
+ err = mpage_readpage(page, ext3_get_block);
+ if ((err == 0) && !PageUptodate(page))
+ wait_on_page_locked(page);
+ lock_page(page);
+ }
+ if (err == 0 && PageUptodate(page)) {
+ kaddr = kmap_atomic(page, KM_USER0);
+ memset(kaddr + offset, 0, length);
+ flush_dcache_page(page);
+ kunmap_atomic(kaddr, KM_USER0);
+ __set_page_dirty_nobuffers(page);
+ goto unlock;
+ }
+ /*
+ * Well, we tried to work without buffers and failed.
+ * Fallback to creating buffers
+ */
+ }
+
if (!page_has_buffers(page))
create_empty_buffers(page, blocksize, 0);
diff -Narup -Xdontdiff linux-2.6.10.org/fs/ext3/super.c
linux-2.6.10.nobh/fs/ext3/super.c
--- linux-2.6.10.org/fs/ext3/super.c 2004-12-24 13:35:28.000000000 -0800
+++ linux-2.6.10.nobh/fs/ext3/super.c 2005-02-25 10:22:58.940466184 -0800
@@ -579,7 +579,7 @@ enum {
Opt_resgid, Opt_resuid, Opt_sb, Opt_err_cont, Opt_err_panic, Opt_err_ro,
Opt_nouid32, Opt_check, Opt_nocheck, Opt_debug, Opt_oldalloc, Opt_orlov,
Opt_user_xattr, Opt_nouser_xattr, Opt_acl, Opt_noacl,
- Opt_reservation, Opt_noreservation, Opt_noload,
+ Opt_reservation, Opt_noreservation, Opt_noload, Opt_nobh,
Opt_commit, Opt_journal_update, Opt_journal_inum,
Opt_abort, Opt_data_journal, Opt_data_ordered, Opt_data_writeback,
Opt_usrjquota, Opt_grpjquota, Opt_offusrjquota, Opt_offgrpjquota,
@@ -614,6 +614,7 @@ static match_table_t tokens = {
{Opt_reservation, "reservation"},
{Opt_noreservation, "noreservation"},
{Opt_noload, "noload"},
+ {Opt_nobh, "nobh"},
{Opt_commit, "commit=%u"},
{Opt_journal_update, "journal=update"},
{Opt_journal_inum, "journal=%u"},
@@ -923,6 +924,9 @@ clear_qf_name:
match_int(&args[0], &option);
*n_blocks_count = option;
break;
+ case Opt_nobh:
+ set_opt (sbi->s_mount_opt, NOBH);
+ break;
default:
printk (KERN_ERR
"EXT3-fs: Unrecognized mount option \"%s\" "
diff -Narup -Xdontdiff linux-2.6.10.org/include/linux/ext3_fs.h
linux-2.6.10.nobh/include/linux/ext3_fs.h
--- linux-2.6.10.org/include/linux/ext3_fs.h 2004-12-24 13:34:58.000000000
-0800
+++ linux-2.6.10.nobh/include/linux/ext3_fs.h 2005-02-25 11:31:31.155700328
-0800
@@ -355,6 +355,7 @@ struct ext3_inode {
#define EXT3_MOUNT_POSIX_ACL 0x08000 /* POSIX Access Control Lists */
#define EXT3_MOUNT_RESERVATION 0x10000 /* Preallocation */
#define EXT3_MOUNT_BARRIER 0x20000 /* Use block barriers */
+#define EXT3_MOUNT_NOBH 0x40000 /* No bufferheads */
/* Compatibility, for having both ext2_fs.h and ext3_fs.h included at once */
#ifndef _LINUX_EXT2_FS_H
