Namjae Jeon <linkinjeon@xxxxxxxxx> writes:
> From: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>
>
> Make the fibmap call the return the proper physical block number for any
> offset request in the fallocated range.
>
> Signed-off-by: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>
> Signed-off-by: Amit Sahrawat <a.sahrawat@xxxxxxxxxxx>
> ---
> fs/fat/cache.c | 13 ++++++++++---
> fs/fat/fat.h | 3 +++
> fs/fat/inode.c | 3 +++
> 3 files changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/fs/fat/cache.c b/fs/fat/cache.c
> index a132666..d22c1a2 100644
> --- a/fs/fat/cache.c
> +++ b/fs/fat/cache.c
> @@ -325,19 +325,26 @@ int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
>
> last_block = (i_size_read(inode) + (blocksize - 1)) >> blocksize_bits;
> if (sector >= last_block) {
> - if (!create)
> - return 0;
> -
> /*
> * Both ->mmu_private and ->i_disksize can access
> * on only allocation path. (caller must hold ->i_mutex)
> */
> last_block = (MSDOS_I(inode)->i_disksize + (blocksize - 1))
> >> blocksize_bits;
> + if (!create) {
> + /* Map a block in fallocated region */
> + if (atomic_read(&MSDOS_I(inode)->beyond_isize))
> + if (sector < last_block)
> + goto out_map_cluster;
> +
> + return 0;
> + }
> +
> if (sector >= last_block)
> return 0;
> }
>
> +out_map_cluster:
> cluster = sector >> (sbi->cluster_bits - sb->s_blocksize_bits);
> offset = sector & (sbi->sec_per_clus - 1);
> cluster = fat_bmap_cluster(inode, cluster);
> diff --git a/fs/fat/fat.h b/fs/fat/fat.h
> index 7b5851f..b884276 100644
> --- a/fs/fat/fat.h
> +++ b/fs/fat/fat.h
> @@ -129,6 +129,9 @@ struct msdos_inode_info {
> struct hlist_node i_dir_hash; /* hash by i_logstart */
> struct rw_semaphore truncate_lock; /* protect bmap against truncate */
> struct inode vfs_inode;
> +
> + /* for getting block number beyond file size in case of fallocate */
> + atomic_t beyond_isize;
> };
>
> struct fat_slot_info {
> diff --git a/fs/fat/inode.c b/fs/fat/inode.c
> index 3636617..1c3192b 100644
> --- a/fs/fat/inode.c
> +++ b/fs/fat/inode.c
> @@ -256,7 +256,10 @@ static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
>
> /* fat_get_cluster() assumes the requested blocknr isn't truncated. */
> down_read(&MSDOS_I(mapping->host)->truncate_lock);
> + /* To get block number beyond file size in fallocated region */
> + atomic_set(&MSDOS_I(mapping->host)->beyond_isize, 1);
> blocknr = generic_block_bmap(mapping, block, fat_get_block);
> + atomic_set(&MSDOS_I(mapping->host)->beyond_isize, 0);
> up_read(&MSDOS_I(mapping->host)->truncate_lock);
This is racy. While user is using bmap, kernel can allocate new blocks.
We should use another function for this.
For example, something like
fat_get_block_bmap()
{
[...]
fat_get_block2(inode, iblock, &max_blocks, bh_result, create, bmap);
[...]
}
blocknr = generic_block_bmap(mapping, block, fat_get_block_bmap);
--
OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
