btrfs-progs: convert: use exact size for reading superblock

We've passed blocksize to prepare_system_chunk and used it to read and
write superblock. While this does not cause a bug (SUPER_INFO is
blocksize ie. page size on most arches), we should really use the
correct size.

Signed-off-by: David Sterba <dsterba@suse.cz>

diff --git a/btrfs-convert.c b/btrfs-convert.c
index d742307..b176f7b 100644 (file)
--- a/btrfs-convert.c
+++ b/btrfs-convert.c
@@ -1799,20 +1799,20 @@ static int prepare_system_chunk_sb(struct btrfs_super_block *super)
        return 0;
 }
 
-static int prepare_system_chunk(int fd, u64 sb_bytenr, u32 sectorsize)
+static int prepare_system_chunk(int fd, u64 sb_bytenr)
 {
        int ret;
        struct extent_buffer *buf;
        struct btrfs_super_block *super;
 
-       BUG_ON(sectorsize < sizeof(*super));
-       buf = malloc(sizeof(*buf) + sectorsize);
+       BUG_ON(BTRFS_SUPER_INFO_SIZE < sizeof(*super));
+       buf = malloc(sizeof(*buf) + BTRFS_SUPER_INFO_SIZE);
        if (!buf)
                return -ENOMEM;
 
-       buf->len = sectorsize;
-       ret = pread(fd, buf->data, sectorsize, sb_bytenr);
-       if (ret != sectorsize)
+       buf->len = BTRFS_SUPER_INFO_SIZE;
+       ret = pread(fd, buf->data, BTRFS_SUPER_INFO_SIZE, sb_bytenr);
+       if (ret != BTRFS_SUPER_INFO_SIZE)
                goto fail;
 
        super = (struct btrfs_super_block *)buf->data;
@@ -1824,8 +1824,8 @@ static int prepare_system_chunk(int fd, u64 sb_bytenr, u32 sectorsize)
                goto fail;
 
        csum_tree_block_size(buf, BTRFS_CRC32_SIZE, 0);
-       ret = pwrite(fd, buf->data, sectorsize, sb_bytenr);
-       if (ret != sectorsize)
+       ret = pwrite(fd, buf->data, BTRFS_SUPER_INFO_SIZE, sb_bytenr);
+       if (ret != BTRFS_SUPER_INFO_SIZE)
                goto fail;
 
        ret = 0;
@@ -2330,7 +2330,7 @@ static int do_convert(const char *devname, int datacsum, int packing, int noxatt
                goto fail;
        }
        /* create a system chunk that maps the whole device */
-       ret = prepare_system_chunk(fd, super_bytenr, blocksize);
+       ret = prepare_system_chunk(fd, super_bytenr);
        if (ret) {
                fprintf(stderr, "unable to update system chunk\n");
                goto fail;