Good day,
please review ...
thanks, Alex
Basic delayed allocation in ext4
Two special ->get_block() methods are introduced:
* ext4_da_get_block_prep()
to be used with ->prepare_write(), defers allocation till flush
* ext4_da_get_block_write()
to be used with mpage_da_writepages(), allocate blocks and correct on-disk
size
Current implementation works with data=writeback only, you should
mount filesystem with delalloc,data=writeback options.
TODO:
* reservation
* data=ordered
* quota
* bmap
Signed-off-by: Alex Tomas <[EMAIL PROTECTED]>
Index: linux-2.6.22/include/linux/ext4_fs.h
===================================================================
--- linux-2.6.22.orig/include/linux/ext4_fs.h 2007-07-26 12:30:25.000000000
+0400
+++ linux-2.6.22/include/linux/ext4_fs.h 2007-07-26 12:32:04.000000000
+0400
@@ -488,6 +488,7 @@ do {
\
#define EXT4_MOUNT_EXTENTS 0x400000 /* Extents support */
#define EXT4_MOUNT_JOURNAL_CHECKSUM 0x800000 /* Journal checksums */
#define EXT4_MOUNT_JOURNAL_ASYNC_COMMIT 0x1000000 /* Journal Async
Commit */
+#define EXT4_MOUNT_DELALLOC 0x2000000 /* Delalloc support */
/* Compatibility, for having both ext2_fs.h and ext4_fs.h included at once */
#ifndef _LINUX_EXT2_FS_H
#define clear_opt(o, opt) o &= ~EXT4_MOUNT_##opt
Index: linux-2.6.22/fs/ext4/super.c
===================================================================
--- linux-2.6.22.orig/fs/ext4/super.c 2007-07-26 12:30:25.000000000 +0400
+++ linux-2.6.22/fs/ext4/super.c 2007-07-26 12:32:04.000000000 +0400
@@ -728,7 +728,7 @@ enum {
Opt_usrjquota, Opt_grpjquota, Opt_offusrjquota, Opt_offgrpjquota,
Opt_jqfmt_vfsold, Opt_jqfmt_vfsv0, Opt_quota, Opt_noquota,
Opt_ignore, Opt_barrier, Opt_err, Opt_resize, Opt_usrquota,
- Opt_grpquota, Opt_extents, Opt_noextents,
+ Opt_grpquota, Opt_extents, Opt_noextents, Opt_delalloc,
};
static match_table_t tokens = {
@@ -782,6 +782,7 @@ static match_table_t tokens = {
{Opt_barrier, "barrier=%u"},
{Opt_extents, "extents"},
{Opt_noextents, "noextents"},
+ {Opt_delalloc, "delalloc"},
{Opt_err, NULL},
{Opt_resize, "resize"},
};
@@ -1127,6 +1128,9 @@ clear_qf_name:
case Opt_noextents:
clear_opt (sbi->s_mount_opt, EXTENTS);
break;
+ case Opt_delalloc:
+ set_opt (sbi->s_mount_opt, DELALLOC);
+ break;
default:
printk (KERN_ERR
"EXT4-fs: Unrecognized mount option \"%s\" "
Index: linux-2.6.22/fs/ext4/inode.c
===================================================================
--- linux-2.6.22.orig/fs/ext4/inode.c 2007-07-26 12:30:22.000000000 +0400
+++ linux-2.6.22/fs/ext4/inode.c 2007-07-26 12:32:04.000000000 +0400
@@ -39,6 +39,8 @@
#include "xattr.h"
#include "acl.h"
+static void ext4_invalidatepage(struct page *page, unsigned long offset);
+
/*
* Test whether an inode is a fast symlink.
*/
@@ -1291,6 +1293,142 @@ static int ext4_journalled_commit_write(
}
/*
+ * this is a special callback for ->prepare_write() only
+ * it's intention is to return mapped block or reserve space
+ */
+static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
+ struct buffer_head *bh_result, int create)
+{
+ int ret = 0;
+
+ BUG_ON(create == 0);
+ BUG_ON(bh_result->b_size != inode->i_sb->s_blocksize);
+
+ /* first, we need to know whether the block is allocated already
+ * XXX: when the filesystem has a lot of free blocks, we could
+ * reserve even allocated blocks to save this lookup */
+ ret = ext4_get_blocks_wrap(NULL, inode, iblock, 1, bh_result, 0, 0);
+ if (ret >= 0) {
+ if (buffer_mapped(bh_result)) {
+ bh_result->b_size = (ret << inode->i_blkbits);
+ } else {
+ /* OK, the block isn't allocated yet, let's reserve
space */
+ /* XXX: call reservation here */
+ /* XXX: __block_prepare_write() unmaps passed block, is
it OK? */
+ map_bh(bh_result, inode->i_sb, 0);
+ set_buffer_new(bh_result);
+ set_buffer_delay(bh_result);
+ }
+ ret = 0;
+ }
+
+ return ret;
+}
+
+
+static int ext4_da_prepare_write(struct file *file, struct page *page,
+ unsigned from, unsigned to)
+{
+ return block_prepare_write(page, from, to, ext4_da_get_block_prep);
+}
+
+static int ext4_da_get_block_write(struct inode *inode, sector_t iblock,
+ struct buffer_head *bh_result, int create)
+{
+ int ret, needed_blocks = ext4_writepage_trans_blocks(inode);
+ unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
+ loff_t disksize = EXT4_I(inode)->i_disksize;
+ handle_t *handle = NULL;
+
+ if (create) {
+ handle = ext4_journal_start(inode, needed_blocks);
+ if (IS_ERR(handle)) {
+ ret = PTR_ERR(handle);
+ goto out;
+ }
+ }
+
+ ret = ext4_get_blocks_wrap(handle, inode, iblock,
+ max_blocks, bh_result, create, 0);
+ if (ret > 0) {
+ bh_result->b_size = (ret << inode->i_blkbits);
+
+ /*
+ * Update on-disk size along with block allocation
+ * we don't use 'extend_disksize' as size may change
+ * within already allocated block -bzzz
+ */
+ disksize = ((loff_t) iblock + ret) << inode->i_blkbits;
+ if (disksize > i_size_read(inode))
+ disksize = i_size_read(inode);
+ if (disksize > EXT4_I(inode)->i_disksize) {
+ /*
+ * XXX: replace with spinlock if seen contended -bzzz
+ */
+ mutex_lock(&EXT4_I(inode)->truncate_mutex);
+ if (disksize > EXT4_I(inode)->i_disksize)
+ EXT4_I(inode)->i_disksize = disksize;
+ mutex_unlock(&EXT4_I(inode)->truncate_mutex);
+
+ if (EXT4_I(inode)->i_disksize == disksize) {
+ if (handle == NULL)
+ handle = ext4_journal_start(inode, 1);
+ if (!IS_ERR(handle))
+ ext4_mark_inode_dirty(handle, inode);
+ }
+ }
+
+ ret = 0;
+ }
+
+out:
+ if (handle && !IS_ERR(handle))
+ ext4_journal_stop(handle);
+
+ return ret;
+}
+
+static int ext4_da_writepages(struct address_space *mapping,
+ struct writeback_control *wbc)
+{
+ return mpage_da_writepages(mapping, wbc, ext4_da_get_block_write);
+}
+
+static void ext4_da_invalidatepage(struct page *page, unsigned long offset)
+{
+ struct buffer_head *head, *bh;
+ unsigned int curr_off = 0;
+
+ /*
+ * Drop reserved blocks
+ */
+ BUG_ON(!PageLocked(page));
+ if (!page_has_buffers(page))
+ goto out;
+
+ bh = head = page_buffers(page);
+ do {
+ unsigned int next_off = curr_off + bh->b_size;
+
+ /*
+ * is this block fully invalidated?
+ */
+ if (offset <= curr_off && buffer_delay(bh)) {
+ clear_buffer_delay(bh);
+ /* XXX: add real stuff here */
+ }
+ curr_off = next_off;
+ bh = bh->b_this_page;
+ } while (bh != head);
+
+out:
+ ext4_invalidatepage(page, offset);
+
+ return;
+}
+
+
+/*
* bmap() is special. It gets used by applications such as lilo and by
* the swapper to find the on-disk block of a specific piece of data.
*
@@ -1741,10 +1879,28 @@ static const struct address_space_operat
.releasepage = ext4_releasepage,
};
+static const struct address_space_operations ext4_da_aops = {
+ .readpage = ext4_readpage,
+ .readpages = ext4_readpages,
+ .writepage = ext4_writeback_writepage,
+ .writepages = ext4_da_writepages,
+ .sync_page = block_sync_page,
+ .prepare_write = ext4_da_prepare_write,
+ .commit_write = generic_commit_write,
+ .bmap = ext4_bmap,
+ .invalidatepage = ext4_da_invalidatepage,
+ .releasepage = ext4_releasepage,
+ .direct_IO = ext4_direct_IO,
+ .migratepage = buffer_migrate_page,
+};
+
void ext4_set_aops(struct inode *inode)
{
if (ext4_should_order_data(inode))
inode->i_mapping->a_ops = &ext4_ordered_aops;
+ else if (ext4_should_writeback_data(inode) &&
+ test_opt(inode->i_sb, DELALLOC))
+ inode->i_mapping->a_ops = &ext4_da_aops;
else if (ext4_should_writeback_data(inode))
inode->i_mapping->a_ops = &ext4_writeback_aops;
else
-
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