speed up ext2 synchronous mounts
PATCH 1/1 speed up ext2 synchronous mounts
At present, when mounted synchronously or with `chattr +S' in effect, ext2 syncs the indirect blocks for every new block when extending a file.
This is not necessary, because a sync is performed on the way out of generic_file_write(). This will pick up all necessary data from inode->i_dirty_buffers and inode->i_dirty_data_buffers, and is sufficient.
The patch removes all the syncing of indirect blocks.
On a non-write-caching scsi disk, an untar of the util-linux tarball runs three times faster. Writing a 100 megabyte file in one megabyte chunks speeds up ten times.
The patch also removes the intermediate indirect block syncing on the truncate() path. Instead, we sync the indirects at a single place, via inode->i_dirty_buffers. This not only means that the writes (may) cluster better. It means that we perform much, much less actual I/O during truncate, because most or all of the indirects will no longer be needed for the file, and will be invalidated.
fsync() and msync() still work correctly. One side effect of this patch is that VM-initiated writepage() against a file hole will no longer block on writeout of indirect blocks. This is good.
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include/linux/ext2_fs_i.h renamed from include/linux/ext2_fs_i.h~ext2-sync-mounts +0 -1
@@ -25,7 +25,6 @@ struct ext2_inode_info {__u32 i_faddr;__u8 i_frag_no;__u8 i_frag_size; -__u16 i_osync;__u32 i_file_acl;__u32 i_dir_acl;__u32 i_dtime;
fs/ext2/inode.c renamed from fs/ext2/inode.c~ext2-sync-mounts +10 -20
@@ -407,10 +407,10 @@ static int ext2_alloc_branch(struct inodmark_buffer_uptodate (bh,1 );unlock_buffer (bh);mark_buffer_dirty_inode (bh, inode); -if (IS_SYNC (inode) || inode->u.ext2_i.i_osync) { -ll_rw_block (WRITE ,1 , &bh); -wait_on_buffer (bh); - } +/* We used to sync bh here if IS_SYNC(inode). +* But we now rely upon generic_osync_inode() +* and b_inode_buffers +*/ parent = nr; }if (n == num)
@@ -469,18 +469,10 @@ static inline int ext2_splice_branch(str inode->i_ctime =CURRENT_TIME ;/* had we spliced it onto indirect block? */ -if (where->bh) { +if (where->bh)mark_buffer_dirty_inode (where->bh, inode); -if (IS_SYNC (inode) || inode->u.ext2_i.i_osync) { -ll_rw_block (WRITE ,1 , &where->bh); -wait_on_buffer (where->bh); - } - } -if (IS_SYNC (inode) || inode->u.ext2_i.i_osync) -ext2_sync_inode (inode); -else -mark_inode_dirty (inode); +mark_inode_dirty (inode);return 0 ; changed:
@@ -837,10 +829,6 @@ void ext2_truncate (struct inode * inode (u32 *)partial->bh->b_data + addr_per_block, (chain+n-1) - partial);mark_buffer_dirty_inode (partial->bh, inode); -if (IS_SYNC (inode)) { -ll_rw_block (WRITE ,1 , &partial->bh); -wait_on_buffer (partial->bh); - }brelse (partial->bh); partial--; }
@@ -872,10 +860,12 @@ do_indirects: ; } inode->i_mtime = inode->i_ctime =CURRENT_TIME ; -if (IS_SYNC (inode)) +if (IS_SYNC (inode)) { +fsync_inode_buffers (inode);ext2_sync_inode (inode); -else + }else {mark_inode_dirty (inode); + } }void ext2_read_inode (struct inode * inode)
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