From 520f16abf003952def5d6b175c56c2b7d5d5b90f Mon Sep 17 00:00:00 2001 From: Omar Sandoval Date: Thu, 22 Sep 2016 17:24:20 -0700 Subject: Btrfs: fix free space tree bitmaps on big-endian systems MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit commit 2fe1d55134fce05c17ea118a2e37a4af771887bc upstream. In convert_free_space_to_{bitmaps,extents}(), we buffer the free space bitmaps in memory and copy them directly to/from the extent buffers with {read,write}_extent_buffer(). The extent buffer bitmap helpers use byte granularity, which is equivalent to a little-endian bitmap. This means that on big-endian systems, the in-memory bitmaps will be written to disk byte-swapped. To fix this, use byte-granularity for the bitmaps in memory. Fixes: a5ed91828518 ("Btrfs: implement the free space B-tree") Tested-by: Holger Hoffstätte Tested-by: Chandan Rajendra Signed-off-by: Omar Sandoval Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/extent_io.c | 64 +++++++++++++++++++++++++++++++++------------- fs/btrfs/extent_io.h | 22 ++++++++++++++++ fs/btrfs/free-space-tree.c | 17 ++++++------ 3 files changed, 76 insertions(+), 27 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 92fe3f8012db..28f60fcefb81 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -5508,17 +5508,45 @@ void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src, } } -/* - * The extent buffer bitmap operations are done with byte granularity because - * bitmap items are not guaranteed to be aligned to a word and therefore a - * single word in a bitmap may straddle two pages in the extent buffer. - */ -#define BIT_BYTE(nr) ((nr) / BITS_PER_BYTE) -#define BYTE_MASK ((1 << BITS_PER_BYTE) - 1) -#define BITMAP_FIRST_BYTE_MASK(start) \ - ((BYTE_MASK << ((start) & (BITS_PER_BYTE - 1))) & BYTE_MASK) -#define BITMAP_LAST_BYTE_MASK(nbits) \ - (BYTE_MASK >> (-(nbits) & (BITS_PER_BYTE - 1))) +void le_bitmap_set(u8 *map, unsigned int start, int len) +{ + u8 *p = map + BIT_BYTE(start); + const unsigned int size = start + len; + int bits_to_set = BITS_PER_BYTE - (start % BITS_PER_BYTE); + u8 mask_to_set = BITMAP_FIRST_BYTE_MASK(start); + + while (len - bits_to_set >= 0) { + *p |= mask_to_set; + len -= bits_to_set; + bits_to_set = BITS_PER_BYTE; + mask_to_set = ~(u8)0; + p++; + } + if (len) { + mask_to_set &= BITMAP_LAST_BYTE_MASK(size); + *p |= mask_to_set; + } +} + +void le_bitmap_clear(u8 *map, unsigned int start, int len) +{ + u8 *p = map + BIT_BYTE(start); + const unsigned int size = start + len; + int bits_to_clear = BITS_PER_BYTE - (start % BITS_PER_BYTE); + u8 mask_to_clear = BITMAP_FIRST_BYTE_MASK(start); + + while (len - bits_to_clear >= 0) { + *p &= ~mask_to_clear; + len -= bits_to_clear; + bits_to_clear = BITS_PER_BYTE; + mask_to_clear = ~(u8)0; + p++; + } + if (len) { + mask_to_clear &= BITMAP_LAST_BYTE_MASK(size); + *p &= ~mask_to_clear; + } +} /* * eb_bitmap_offset() - calculate the page and offset of the byte containing the @@ -5562,7 +5590,7 @@ static inline void eb_bitmap_offset(struct extent_buffer *eb, int extent_buffer_test_bit(struct extent_buffer *eb, unsigned long start, unsigned long nr) { - char *kaddr; + u8 *kaddr; struct page *page; unsigned long i; size_t offset; @@ -5584,13 +5612,13 @@ int extent_buffer_test_bit(struct extent_buffer *eb, unsigned long start, void extent_buffer_bitmap_set(struct extent_buffer *eb, unsigned long start, unsigned long pos, unsigned long len) { - char *kaddr; + u8 *kaddr; struct page *page; unsigned long i; size_t offset; const unsigned int size = pos + len; int bits_to_set = BITS_PER_BYTE - (pos % BITS_PER_BYTE); - unsigned int mask_to_set = BITMAP_FIRST_BYTE_MASK(pos); + u8 mask_to_set = BITMAP_FIRST_BYTE_MASK(pos); eb_bitmap_offset(eb, start, pos, &i, &offset); page = eb->pages[i]; @@ -5601,7 +5629,7 @@ void extent_buffer_bitmap_set(struct extent_buffer *eb, unsigned long start, kaddr[offset] |= mask_to_set; len -= bits_to_set; bits_to_set = BITS_PER_BYTE; - mask_to_set = ~0U; + mask_to_set = ~(u8)0; if (++offset >= PAGE_SIZE && len > 0) { offset = 0; page = eb->pages[++i]; @@ -5626,13 +5654,13 @@ void extent_buffer_bitmap_set(struct extent_buffer *eb, unsigned long start, void extent_buffer_bitmap_clear(struct extent_buffer *eb, unsigned long start, unsigned long pos, unsigned long len) { - char *kaddr; + u8 *kaddr; struct page *page; unsigned long i; size_t offset; const unsigned int size = pos + len; int bits_to_clear = BITS_PER_BYTE - (pos % BITS_PER_BYTE); - unsigned int mask_to_clear = BITMAP_FIRST_BYTE_MASK(pos); + u8 mask_to_clear = BITMAP_FIRST_BYTE_MASK(pos); eb_bitmap_offset(eb, start, pos, &i, &offset); page = eb->pages[i]; @@ -5643,7 +5671,7 @@ void extent_buffer_bitmap_clear(struct extent_buffer *eb, unsigned long start, kaddr[offset] &= ~mask_to_clear; len -= bits_to_clear; bits_to_clear = BITS_PER_BYTE; - mask_to_clear = ~0U; + mask_to_clear = ~(u8)0; if (++offset >= PAGE_SIZE && len > 0) { offset = 0; page = eb->pages[++i]; diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h index c0c1c4fef6ce..d19010729468 100644 --- a/fs/btrfs/extent_io.h +++ b/fs/btrfs/extent_io.h @@ -58,6 +58,28 @@ */ #define EXTENT_PAGE_PRIVATE 1 +/* + * The extent buffer bitmap operations are done with byte granularity instead of + * word granularity for two reasons: + * 1. The bitmaps must be little-endian on disk. + * 2. Bitmap items are not guaranteed to be aligned to a word and therefore a + * single word in a bitmap may straddle two pages in the extent buffer. + */ +#define BIT_BYTE(nr) ((nr) / BITS_PER_BYTE) +#define BYTE_MASK ((1 << BITS_PER_BYTE) - 1) +#define BITMAP_FIRST_BYTE_MASK(start) \ + ((BYTE_MASK << ((start) & (BITS_PER_BYTE - 1))) & BYTE_MASK) +#define BITMAP_LAST_BYTE_MASK(nbits) \ + (BYTE_MASK >> (-(nbits) & (BITS_PER_BYTE - 1))) + +static inline int le_test_bit(int nr, const u8 *addr) +{ + return 1U & (addr[BIT_BYTE(nr)] >> (nr & (BITS_PER_BYTE-1))); +} + +extern void le_bitmap_set(u8 *map, unsigned int start, int len); +extern void le_bitmap_clear(u8 *map, unsigned int start, int len); + struct extent_state; struct btrfs_root; struct btrfs_io_bio; diff --git a/fs/btrfs/free-space-tree.c b/fs/btrfs/free-space-tree.c index 53dbeaf6ce94..68ce45a2b763 100644 --- a/fs/btrfs/free-space-tree.c +++ b/fs/btrfs/free-space-tree.c @@ -151,7 +151,7 @@ static inline u32 free_space_bitmap_size(u64 size, u32 sectorsize) return DIV_ROUND_UP((u32)div_u64(size, sectorsize), BITS_PER_BYTE); } -static unsigned long *alloc_bitmap(u32 bitmap_size) +static u8 *alloc_bitmap(u32 bitmap_size) { void *mem; @@ -180,8 +180,7 @@ int convert_free_space_to_bitmaps(struct btrfs_trans_handle *trans, struct btrfs_free_space_info *info; struct btrfs_key key, found_key; struct extent_buffer *leaf; - unsigned long *bitmap; - char *bitmap_cursor; + u8 *bitmap, *bitmap_cursor; u64 start, end; u64 bitmap_range, i; u32 bitmap_size, flags, expected_extent_count; @@ -231,7 +230,7 @@ int convert_free_space_to_bitmaps(struct btrfs_trans_handle *trans, block_group->sectorsize); last = div_u64(found_key.objectid + found_key.offset - start, block_group->sectorsize); - bitmap_set(bitmap, first, last - first); + le_bitmap_set(bitmap, first, last - first); extent_count++; nr++; @@ -269,7 +268,7 @@ int convert_free_space_to_bitmaps(struct btrfs_trans_handle *trans, goto out; } - bitmap_cursor = (char *)bitmap; + bitmap_cursor = bitmap; bitmap_range = block_group->sectorsize * BTRFS_FREE_SPACE_BITMAP_BITS; i = start; while (i < end) { @@ -318,7 +317,7 @@ int convert_free_space_to_extents(struct btrfs_trans_handle *trans, struct btrfs_free_space_info *info; struct btrfs_key key, found_key; struct extent_buffer *leaf; - unsigned long *bitmap; + u8 *bitmap; u64 start, end; /* Initialize to silence GCC. */ u64 extent_start = 0; @@ -362,7 +361,7 @@ int convert_free_space_to_extents(struct btrfs_trans_handle *trans, break; } else if (found_key.type == BTRFS_FREE_SPACE_BITMAP_KEY) { unsigned long ptr; - char *bitmap_cursor; + u8 *bitmap_cursor; u32 bitmap_pos, data_size; ASSERT(found_key.objectid >= start); @@ -372,7 +371,7 @@ int convert_free_space_to_extents(struct btrfs_trans_handle *trans, bitmap_pos = div_u64(found_key.objectid - start, block_group->sectorsize * BITS_PER_BYTE); - bitmap_cursor = ((char *)bitmap) + bitmap_pos; + bitmap_cursor = bitmap + bitmap_pos; data_size = free_space_bitmap_size(found_key.offset, block_group->sectorsize); @@ -409,7 +408,7 @@ int convert_free_space_to_extents(struct btrfs_trans_handle *trans, offset = start; bitnr = 0; while (offset < end) { - bit = !!test_bit(bitnr, bitmap); + bit = !!le_test_bit(bitnr, bitmap); if (prev_bit == 0 && bit == 1) { extent_start = offset; } else if (prev_bit == 1 && bit == 0) { -- cgit v1.2.3