[PATCH v2] fs/libfs: don't assume blocksize <= PAGE_SIZE in generic_check_addressable

[PATCH v2] fs/libfs: don't assume blocksize <= PAGE_SIZE in generic_check_addressable

[Pankaj Raghav]

Since [1], it is possible for filesystems to have blocksize > PAGE_SIZE
of the system.

Remove the assumption and make the check generic for all blocksizes in
generic_check_addressable().

[1] https://lore.kernel.org/linux-xfs/20240822135018.1931258-1-kernel@pankajraghav.com/

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
---
Changes since v1:
- Removed the unnecessary parantheses.
- Added RVB from Jan Kara (Thanks).

 fs/libfs.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/fs/libfs.c b/fs/libfs.c
index 4d1862f589e8..f99ecc300647 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -1584,13 +1584,17 @@ EXPORT_SYMBOL(generic_file_fsync);
 int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)
 {
 	u64 last_fs_block = num_blocks - 1;
-	u64 last_fs_page =
-		last_fs_block >> (PAGE_SHIFT - blocksize_bits);
+	u64 last_fs_page, max_bytes;
+
+	if (check_shl_overflow(num_blocks, blocksize_bits, &max_bytes))
+		return -EFBIG;
+
+	last_fs_page = (max_bytes >> PAGE_SHIFT) - 1;
 
 	if (unlikely(num_blocks == 0))
 		return 0;
 
-	if ((blocksize_bits < 9) || (blocksize_bits > PAGE_SHIFT))
+	if (blocksize_bits < 9)
 		return -EINVAL;
 
 	if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||

base-commit: b39f7d75dc41b5f5d028192cd5d66cff71179f35
-- 
2.49.0

Re: [PATCH v2] fs/libfs: don't assume blocksize <= PAGE_SIZE in generic_check_addressable

[Baokun Li]

On 2025/6/30 18:40, Pankaj Raghav wrote:
> Since [1], it is possible for filesystems to have blocksize > PAGE_SIZE
> of the system.
>
> Remove the assumption and make the check generic for all blocksizes in
> generic_check_addressable().
>
> [1] https://lore.kernel.org/linux-xfs/20240822135018.1931258-1-kernel@pankajraghav.com/
>
> Reviewed-by: Jan Kara <jack@suse.cz>
> Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>

Looks good. Feel free to add:

Reviewed-by: Baokun Li <libaokun1@huawei.com>

> ---
> Changes since v1:
> - Removed the unnecessary parantheses.
> - Added RVB from Jan Kara (Thanks).
>
>   fs/libfs.c | 10 +++++++---
>   1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/fs/libfs.c b/fs/libfs.c
> index 4d1862f589e8..f99ecc300647 100644
> --- a/fs/libfs.c
> +++ b/fs/libfs.c
> @@ -1584,13 +1584,17 @@ EXPORT_SYMBOL(generic_file_fsync);
>   int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)
>   {
>   	u64 last_fs_block = num_blocks - 1;
> -	u64 last_fs_page =
> -		last_fs_block >> (PAGE_SHIFT - blocksize_bits);
> +	u64 last_fs_page, max_bytes;
> +
> +	if (check_shl_overflow(num_blocks, blocksize_bits, &max_bytes))
> +		return -EFBIG;
> +
> +	last_fs_page = (max_bytes >> PAGE_SHIFT) - 1;
>   
>   	if (unlikely(num_blocks == 0))
>   		return 0;
>   
> -	if ((blocksize_bits < 9) || (blocksize_bits > PAGE_SHIFT))
> +	if (blocksize_bits < 9)
>   		return -EINVAL;
>   
>   	if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||
>
> base-commit: b39f7d75dc41b5f5d028192cd5d66cff71179f35

Re: [PATCH v2] fs/libfs: don't assume blocksize <= PAGE_SIZE in generic_check_addressable

[Zhang Yi]

On 2025/6/30 18:40, Pankaj Raghav wrote:
> Since [1], it is possible for filesystems to have blocksize > PAGE_SIZE
> of the system.
> 
> Remove the assumption and make the check generic for all blocksizes in
> generic_check_addressable().
> 
> [1] https://lore.kernel.org/linux-xfs/20240822135018.1931258-1-kernel@pankajraghav.com/
> 
> Reviewed-by: Jan Kara <jack@suse.cz>
> Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>

Looks good to me.

Reviewed-by: Zhang Yi <yi.zhang@huawei.com>

> ---
> Changes since v1:
> - Removed the unnecessary parantheses.
> - Added RVB from Jan Kara (Thanks).
> 
>  fs/libfs.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/libfs.c b/fs/libfs.c
> index 4d1862f589e8..f99ecc300647 100644
> --- a/fs/libfs.c
> +++ b/fs/libfs.c
> @@ -1584,13 +1584,17 @@ EXPORT_SYMBOL(generic_file_fsync);
>  int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)
>  {
>  	u64 last_fs_block = num_blocks - 1;
> -	u64 last_fs_page =
> -		last_fs_block >> (PAGE_SHIFT - blocksize_bits);
> +	u64 last_fs_page, max_bytes;
> +
> +	if (check_shl_overflow(num_blocks, blocksize_bits, &max_bytes))
> +		return -EFBIG;
> +
> +	last_fs_page = (max_bytes >> PAGE_SHIFT) - 1;
>  
>  	if (unlikely(num_blocks == 0))
>  		return 0;
>  
> -	if ((blocksize_bits < 9) || (blocksize_bits > PAGE_SHIFT))
> +	if (blocksize_bits < 9)
>  		return -EINVAL;
>  
>  	if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||
> 
> base-commit: b39f7d75dc41b5f5d028192cd5d66cff71179f35

Re: [PATCH v2] fs/libfs: don't assume blocksize <= PAGE_SIZE in generic_check_addressable

[Christian Brauner]

On Mon, 30 Jun 2025 12:40:18 +0200, Pankaj Raghav wrote:
> Since [1], it is possible for filesystems to have blocksize > PAGE_SIZE
> of the system.
> 
> Remove the assumption and make the check generic for all blocksizes in
> generic_check_addressable().
> 
> [1] https://lore.kernel.org/linux-xfs/20240822135018.1931258-1-kernel@pankajraghav.com/
> 
> [...]

Applied to the vfs-6.17.misc branch of the vfs/vfs.git tree.
Patches in the vfs-6.17.misc branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs-6.17.misc

[1/1] fs/libfs: don't assume blocksize <= PAGE_SIZE in generic_check_addressable
      https://git.kernel.org/vfs/vfs/c/c2d3651387f8