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hpfs: implement prefetch to improve performance

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This patch implements prefetch to improve performance.  It helps mostly
when scanning the bitmaps to calculate free space.

Signed-off-by: Mikulas Patocka <mpatocka@artax.karlin.mff.cuni.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mikulas Patocka
2013-07-04 19:04:01 +02:00
committed by Linus Torvalds
parent a0c1b75963
commit 275f495dbe
4 changed files with 63 additions and 5 deletions
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19
fs/hpfs/map.c
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@@ -17,6 +17,7 @@ __le32 *hpfs_map_bitmap(struct super_block *s, unsigned bmp_block,
struct quad_buffer_head *qbh, char *id)
{
secno sec;
__le32 *ret;
unsigned n_bands = (hpfs_sb(s)->sb_fs_size + 0x3fff) >> 14;
if (hpfs_sb(s)->sb_chk) if (bmp_block >= n_bands) {
hpfs_error(s, "hpfs_map_bitmap called with bad parameter: %08x at %s", bmp_block, id);
@@ -27,7 +28,23 @@ __le32 *hpfs_map_bitmap(struct super_block *s, unsigned bmp_block,
hpfs_error(s, "invalid bitmap block pointer %08x -> %08x at %s", bmp_block, sec, id);
return NULL;
}
return hpfs_map_4sectors(s, sec, qbh, 4);
ret = hpfs_map_4sectors(s, sec, qbh, 4);
if (ret) hpfs_prefetch_bitmap(s, bmp_block + 1);
return ret;
}
void hpfs_prefetch_bitmap(struct super_block *s, unsigned bmp_block)
{
unsigned to_prefetch, next_prefetch;
unsigned n_bands = (hpfs_sb(s)->sb_fs_size + 0x3fff) >> 14;
if (unlikely(bmp_block >= n_bands))
return;
to_prefetch = le32_to_cpu(hpfs_sb(s)->sb_bmp_dir[bmp_block]);
if (unlikely(bmp_block + 1 >= n_bands))
next_prefetch = 0;
else
next_prefetch = le32_to_cpu(hpfs_sb(s)->sb_bmp_dir[bmp_block + 1]);
hpfs_prefetch_sectors(s, to_prefetch, 4 + 4 * (to_prefetch + 4 == next_prefetch));
}
/*