The patch titled
fs/inode.c: properly init address_space->writeback_index
has been added to the -mm tree. Its filename is
fs-inodec-properly-init-address_space-writeback_index.patch
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------------------------------------------------------
Subject: fs/inode.c: properly init address_space->writeback_index
From: Chris Mason <chris.mason@xxxxxxxxxx>
write_cache_pages() uses i_mapping->writeback_index to pick up where it
left off the last time a given inode was found by pdflush or
balance_dirty_pages (or anyone else who sets wbc->range_cyclic)
alloc_inode() should set it to a sane value so that writeback doesn't
start in the middle of a file. It is somewhat difficult to notice the bug
since write_cache_pages will loop around to the start of the file and the
elevator helps hide the resulting seeks.
For whatever reason, Btrfs hits this often. Unpatched, untarring 30
copies of the linux kernel in series runs at 47MB/s on a single sata
drive. With this fix, it jumps to 62MB/s.
Signed-off-by: Chris Mason <chris.mason@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/inode.c | 1 +
1 file changed, 1 insertion(+)
diff -puN fs/inode.c~fs-inodec-properly-init-address_space-writeback_index fs/inode.c
--- a/fs/inode.c~fs-inodec-properly-init-address_space-writeback_index
+++ a/fs/inode.c
@@ -166,6 +166,7 @@ static struct inode *alloc_inode(struct
mapping_set_gfp_mask(mapping, GFP_HIGHUSER_PAGECACHE);
mapping->assoc_mapping = NULL;
mapping->backing_dev_info = &default_backing_dev_info;
+ mapping->writeback_index = 0;
/*
* If the block_device provides a backing_dev_info for client
_
Patches currently in -mm which might be from chris.mason@xxxxxxxxxx are
fs-inodec-properly-init-address_space-writeback_index.patch
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