Namjae Jeon <linkinj...@gmail.com> writes:

> diff --git a/fs/fat/cache.c b/fs/fat/cache.c
> index c56bd7e..7777822 100644
> --- a/fs/fat/cache.c
> +++ b/fs/fat/cache.c
> @@ -312,6 +312,7 @@ int fat_bmap(struct inode *inode, sector_t sector, 
> sector_t *phys,
>       const unsigned char blocksize_bits = sb->s_blocksize_bits;
>       sector_t last_block;
>       int cluster, offset;
> +     loff_t i_size = i_size_read(inode);
>  
>       *phys = 0;
>       *mapped_blocks = 0;
> @@ -323,10 +324,20 @@ int fat_bmap(struct inode *inode, sector_t sector, 
> sector_t *phys,
>               return 0;
>       }
>  
> -     last_block = (i_size_read(inode) + (blocksize - 1)) >> blocksize_bits;
> +     last_block = (i_size + (blocksize - 1)) >> blocksize_bits;
>       if (sector >= last_block) {
> -             if (!create)
> +             if (!create) {
> +                     /*
> +                      * to map cluster in case of read request
> +                      * for a block in fallocated region
> +                      */
> +                     if (MSDOS_I(inode)->i_disksize >
> +                         round_up(i_size, sb->s_blocksize)) {
> +                             goto out_map_cluster;
> +                     }

Said on another reply though, we will have to add new flag for
this. Because normal read get_block() operation should not return
mapping beyond ->i_size.

>       /* fat_get_cluster() assumes the requested blocknr isn't truncated. */
> -     down_read(&MSDOS_I(mapping->host)->truncate_lock);
> +     mutex_lock(&mapping->host->i_mutex);
>       blocknr = generic_block_bmap(mapping, block, fat_get_block);
> -     up_read(&MSDOS_I(mapping->host)->truncate_lock);
> +     mutex_unlock(&mapping->host->i_mutex);
>  
>       return blocknr;
>  }

->i_mutex doesn't work for swapfile.
-- 
OGAWA Hirofumi <hirof...@mail.parknet.co.jp>
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