[PATCH] ext3: Check return value of sb_getblk()

[PATCH] ext3: Check return value of sb_getblk()

[Namhyung Kim]

Check return value of sb_getblk() is NULL. unlikely is addded here
since it is called from a loop and we've been OK without the check
until now.

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
---
 fs/ext3/inode.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
index ef1c23a..a7ac778 100644
--- a/fs/ext3/inode.c
+++ b/fs/ext3/inode.c
@@ -655,6 +655,12 @@ static int ext3_alloc_branch(handle_t *handle, struct inode *inode,
 		 * parent to disk.
 		 */
 		bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
+		if (unlikely(!bh)) {
+			n--;
+			err = -ENOMEM;
+			goto failed;
+		}
+
 		branch[n].bh = bh;
 		lock_buffer(bh);
 		BUFFER_TRACE(bh, "call get_create_access");
-- 
1.7.0.4

Re: [PATCH] ext3: Check return value of sb_getblk()

[Namhyung Kim]

2010-10-19 (화), 15:34 +0900, Namhyung Kim:
> Check return value of sb_getblk() is NULL. unlikely is addded here
> since it is called from a loop and we've been OK without the check
> until now.
> 
> Signed-off-by: Namhyung Kim <namhyung@gmail.com>
> ---
>  fs/ext3/inode.c |    6 ++++++
>  1 files changed, 6 insertions(+), 0 deletions(-)
> 
> diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
> index ef1c23a..a7ac778 100644
> --- a/fs/ext3/inode.c
> +++ b/fs/ext3/inode.c
> @@ -655,6 +655,12 @@ static int ext3_alloc_branch(handle_t *handle, struct inode *inode,
>  		 * parent to disk.
>  		 */
>  		bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
> +		if (unlikely(!bh)) {
> +			n--;
> +			err = -ENOMEM;
> +			goto failed;
> +		}
> +
>  		branch[n].bh = bh;
>  		lock_buffer(bh);
>  		BUFFER_TRACE(bh, "call get_create_access");

Maybe EIO would be more proper error code, I guess.


-- 
Regards,
Namhyung Kim


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Re: [PATCH] ext3: Check return value of sb_getblk()

[Jan Kara]

On Tue 19-10-10 16:57:29, Namhyung Kim wrote:
> 2010-10-19 (화), 15:34 +0900, Namhyung Kim:
> > Check return value of sb_getblk() is NULL. unlikely is addded here
> > since it is called from a loop and we've been OK without the check
> > until now.
> > 
> > Signed-off-by: Namhyung Kim <namhyung@gmail.com>
> > ---
> >  fs/ext3/inode.c |    6 ++++++
> >  1 files changed, 6 insertions(+), 0 deletions(-)
> > 
> > diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
> > index ef1c23a..a7ac778 100644
> > --- a/fs/ext3/inode.c
> > +++ b/fs/ext3/inode.c
> > @@ -655,6 +655,12 @@ static int ext3_alloc_branch(handle_t *handle, struct inode *inode,
> >  		 * parent to disk.
> >  		 */
> >  		bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
> > +		if (unlikely(!bh)) {
> > +			n--;
> > +			err = -ENOMEM;
> > +			goto failed;
> > +		}
> > +
> >  		branch[n].bh = bh;
> >  		lock_buffer(bh);
> >  		BUFFER_TRACE(bh, "call get_create_access");
> 
> Maybe EIO would be more proper error code, I guess.
  Hmm, for ext3, sb_getblk() cannot really realistically fail. Block
numbers are 32-bit so they can never be big enough to overflow pagecache
index and grow_buffers() loops indefinitely if it cannot allocate buffers.
But OK, EIO might be a reasonable return value and we can have the check
there just in case sb_getblk() grows some other possiblility to fail.

								Honza

-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR
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