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Btrfs: stop using highmem for extent_buffers

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The extent_buffers have a very complex interface where
we use HIGHMEM for metadata and try to cache a kmap mapping
to access the memory.

The next commit adds reader/writer locks, and concurrent use
of this kmap cache would make it even more complex.

This commit drops the ability to use HIGHMEM with extent buffers,
and rips out all of the related code.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason 2011-07-19 12:04:14 -04:00
parent 199c36eaa9
commit a65917156e
7 changed files with 52 additions and 378 deletions
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7
fs/btrfs/disk-io.c
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@ -217,7 +217,6 @@ static int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf,
unsigned long len;
unsigned long cur_len;
unsigned long offset = BTRFS_CSUM_SIZE;
char *map_token = NULL;
char *kaddr;
unsigned long map_start;
unsigned long map_len;
@ -228,8 +227,7 @@ static int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf,
len = buf->len - offset;
while (len > 0) {
err = map_private_extent_buffer(buf, offset, 32,
&map_token, &kaddr,
&map_start, &map_len, KM_USER0);
&kaddr, &map_start, &map_len);
if (err)
return 1;
cur_len = min(len, map_len - (offset - map_start));
@ -237,7 +235,6 @@ static int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf,
crc, cur_len);
len -= cur_len;
offset += cur_len;
unmap_extent_buffer(buf, map_token, KM_USER0);
}
if (csum_size > sizeof(inline_result)) {
result = kzalloc(csum_size * sizeof(char), GFP_NOFS);
@ -1603,7 +1600,7 @@ struct btrfs_root *open_ctree(struct super_block *sb,
goto fail_bdi;
}
fs_info->btree_inode->i_mapping->flags &= ~__GFP_FS;
mapping_set_gfp_mask(fs_info->btree_inode->i_mapping, GFP_NOFS);
INIT_RADIX_TREE(&fs_info->fs_roots_radix, GFP_ATOMIC);
INIT_LIST_HEAD(&fs_info->trans_list);