diff options
Diffstat (limited to 'fs/squashfs/block.c')
| -rw-r--r-- | fs/squashfs/block.c | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/fs/squashfs/block.c b/fs/squashfs/block.c index 8a75d812ffdf..2eb66decc5ab 100644 --- a/fs/squashfs/block.c +++ b/fs/squashfs/block.c @@ -206,6 +206,22 @@ static void squashfs_bio_end_io(struct bio *bio) kfree(bio_req); } +static int bh_is_optional(struct squashfs_read_request *req, int idx) +{ + int start_idx, end_idx; + struct squashfs_sb_info *msblk = req->sb->s_fs_info; + + start_idx = (idx * msblk->devblksize - req->offset) / PAGE_CACHE_SIZE; + end_idx = ((idx + 1) * msblk->devblksize - req->offset + 1) / PAGE_CACHE_SIZE; + if (start_idx >= req->output->pages) + return 1; + if (start_idx < 0) + start_idx = end_idx; + if (end_idx >= req->output->pages) + end_idx = start_idx; + return !req->output->page[start_idx] && !req->output->page[end_idx]; +} + static int actor_getblks(struct squashfs_read_request *req, u64 block) { int i; @@ -215,6 +231,15 @@ static int actor_getblks(struct squashfs_read_request *req, u64 block) return -ENOMEM; for (i = 0; i < req->nr_buffers; ++i) { + /* + * When dealing with an uncompressed block, the actor may + * contains NULL pages. There's no need to read the buffers + * associated with these pages. + */ + if (!req->compressed && bh_is_optional(req, i)) { + req->bh[i] = NULL; + continue; + } req->bh[i] = sb_getblk(req->sb, block + i); if (!req->bh[i]) { while (--i) { |