From: Omar Sandoval <osandov@xxxxxx>
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.
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Omar Sandoval <osandov@xxxxxx>
---
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 75533adef998..bdb43882791a 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -5514,17 +5514,45 @@ 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
@@ -5568,7 +5596,7 @@ 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;
@@ -5590,13 +5618,13 @@ 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];
@@ -5607,7 +5635,7 @@ 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];
@@ -5632,13 +5660,13 @@ 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];
@@ -5649,7 +5677,7 @@ 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) {
--
2.9.0
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html