On 10/1/18 10:46 PM, Nikolay Borisov wrote:
Those functions are in preparation for adding the freespace tree repair code since it needs to be able to deal with bitmap based fsts. This patch adds extent_buffer_bitmap_set and extent_buffer_bitmap_clear functions. Since in userspace we don't have to deal with page mappings their implementation is vastly simplified by simply setting each bit in the passed range. Signed-off-by: Nikolay Borisov <nbori...@suse.com>
Reviewed-by: Su Yue <suy.f...@cn.fujitsu.com>
--- extent_io.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ extent_io.h | 4 ++++ 2 files changed, 60 insertions(+) diff --git a/extent_io.c b/extent_io.c index 198492699438..de47c2c59ae9 100644 --- a/extent_io.c +++ b/extent_io.c @@ -204,6 +204,62 @@ static int clear_state_bit(struct extent_io_tree *tree, return ret; }+/**+ * extent_buffer_bitmap_set - set an area of a bitmap + * @eb: the extent buffer + * @start: offset of the bitmap item in the extent buffer + * @pos: bit number of the first bit + * @len: number of bits to set + */ +void extent_buffer_bitmap_set(struct extent_buffer *eb, unsigned long start, + unsigned long pos, unsigned long len) +{ + u8 *p = (u8 *)eb->data + start + BIT_BYTE(pos); + const unsigned int size = pos + len; + int bits_to_set = BITS_PER_BYTE - (pos % BITS_PER_BYTE); + u8 mask_to_set = BITMAP_FIRST_BYTE_MASK(pos); + + while (len >= bits_to_set) { + *p |= mask_to_set; + len -= bits_to_set; + bits_to_set = BITS_PER_BYTE; + mask_to_set = ~0; + p++; + } + if (len) { + mask_to_set &= BITMAP_LAST_BYTE_MASK(size); + *p |= mask_to_set; + } +} + + +/** + * extent_buffer_bitmap_clear - clear an area of a bitmap + * @eb: the extent buffer + * @start: offset of the bitmap item in the extent buffer + * @pos: bit number of the first bit + * @len: number of bits to clear + */ +void extent_buffer_bitmap_clear(struct extent_buffer *eb, unsigned long start, + unsigned long pos, unsigned long len) +{ + u8 *p = (u8 *)eb->data + start + BIT_BYTE(pos); + const unsigned int size = pos + len; + int bits_to_clear = BITS_PER_BYTE - (pos % BITS_PER_BYTE); + u8 mask_to_clear = BITMAP_FIRST_BYTE_MASK(pos); + + while (len >= bits_to_clear) { + *p &= ~mask_to_clear; + len -= bits_to_clear; + bits_to_clear = BITS_PER_BYTE; + mask_to_clear = ~0; + p++; + } + if (len) { + mask_to_clear &= BITMAP_LAST_BYTE_MASK(size); + *p &= ~mask_to_clear; + } +} /* * clear some bits on a range in the tree. */ diff --git a/extent_io.h b/extent_io.h index d407d93d617e..b67c6fc40e89 100644 --- a/extent_io.h +++ b/extent_io.h @@ -175,4 +175,8 @@ int read_data_from_disk(struct btrfs_fs_info *info, void *buf, u64 offset, u64 bytes, int mirror); int write_data_to_disk(struct btrfs_fs_info *info, void *buf, u64 offset, u64 bytes, int mirror); +void extent_buffer_bitmap_clear(struct extent_buffer *eb, unsigned long start, + unsigned long pos, unsigned long len); +void extent_buffer_bitmap_set(struct extent_buffer *eb, unsigned long start, + unsigned long pos, unsigned long len); #endif
