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Btrfs: Optimizations for the extent_buffer code

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Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason
2007-10-15 16:14:27 -04:00
parent 5f39d397df
commit 479965d66e
4 changed files with 76 additions and 36 deletions
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11
fs/btrfs/extent_map.c
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@@ -2140,14 +2140,20 @@ void read_extent_buffer(struct extent_buffer *eb, void *dstv,
EXPORT_SYMBOL(read_extent_buffer);
int map_extent_buffer(struct extent_buffer *eb, unsigned long start,
unsigned long min_len,
char **token, char **map,
unsigned long *map_start,
unsigned long *map_len, int km)
{
size_t offset;
size_t offset = start & (PAGE_CACHE_SIZE - 1);
char *kaddr;
size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
unsigned long end_i = (start_offset + start + min_len) >>
PAGE_CACHE_SHIFT;
if (i != end_i)
return -EINVAL;
WARN_ON(start > eb->len);
@@ -2155,8 +2161,7 @@ int map_extent_buffer(struct extent_buffer *eb, unsigned long start,
offset = start_offset;
*map_start = 0;
} else {
offset = 0;
*map_start = (i << PAGE_CACHE_SHIFT) - offset;
*map_start = (i << PAGE_CACHE_SHIFT) - start_offset;
}
// kaddr = kmap_atomic(eb->pages[i], km);