2017-01-23 17:56:09

by Fabian Frédérick

Subject: [PATCH 1/1 linux-next] ext4: atomically read inode size

See i_size_read() comments in include/linux/fs.h

Signed-off-by: Fabian Frederick <[email protected]>
---
fs/ext4/super.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 9d15a62..3746f77 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3798,7 +3798,8 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
goto cantfind_ext4;

/* check blocks count against device size */
- blocks_count = sb->s_bdev->bd_inode->i_size >> sb->s_blocksize_bits;
+ blocks_count = i_size_read(sb->s_bdev->bd_inode) >>
+ sb->s_blocksize_bits;
if (blocks_count && ext4_blocks_count(es) > blocks_count) {
ext4_msg(sb, KERN_WARNING, "bad geometry: block count %llu "
"exceeds size of device (%llu blocks)",
--
2.9.3

2017-01-23 18:26:11

by Theodore Ts'o

Subject: Re: [PATCH 1/1 linux-next] ext4: atomically read inode size

On Mon, Jan 23, 2017 at 06:56:09PM +0100, Fabian Frederick wrote:
> See i_size_read() comments in include/linux/fs.h
>
> Signed-off-by: Fabian Frederick <[email protected]>
> ---
> fs/ext4/super.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 9d15a62..3746f77 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -3798,7 +3798,8 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
> goto cantfind_ext4;
>
> /* check blocks count against device size */
> - blocks_count = sb->s_bdev->bd_inode->i_size >> sb->s_blocksize_bits;
> + blocks_count = i_size_read(sb->s_bdev->bd_inode) >>
> + sb->s_blocksize_bits;
> if (blocks_count && ext4_blocks_count(es) > blocks_count) {
> ext4_msg(sb, KERN_WARNING, "bad geometry: block count %llu "
> "exceeds size of device (%llu blocks)",

Um, this is at mount time, and we're talking about the i_size of the
block device --- which typically isn't moving around a huge amount.

- Ted