Hello
On Thu, 2005-06-16 at 00:09, fs wrote:
> From: fs <[email protected]>
> To: [email protected]
> Cc: [email protected], [email protected], [email protected], [email protected]
> Subject: [iscas-linaccident 50] [PATCH] ReiserFS _get_block_create_0 wrong behavior when I/O fails
> Date: Wed, 15 Jun 2005 15:10:05 -0400
>
> Related FS:
> ReiserFS
>
> Related Files:
> fs/reiserfs/inode.c
>
> Bug description:
> Make a ReiserFS partition in USB storage HDD, create a test file with
> enough size.
> Write a program, do: open(O_RDONLY) - read - close. After each
> operation, pause for a while, such as 3s. Between open and read, unlug the
> USB wire. open returns zero-filled buffer, no error returns.
>
> Bug analysis:
> do_mpage_readpage will call FS-specific get_block to get buffer mapped
> from disk. reiserfs_get_block doesn't return non-zero when I/O failure occurs.
> reiserfs_get_block -> _get_block_create_0 -> search_by_position_by_key
> search_by_position_by_key returns IO_ERROR, but the original code just simply
> returns 0
>
> research:
> if (search_for_position_by_key (inode->i_sb, &key, &path) != POSITION_FOUND) {
> pathrelse (&path);
> if (p)
> kunmap(bh_result->b_page) ;
> // We do not return -ENOENT if there is a hole but page is uptodate, because it means
> // That there is some MMAPED data associated with it that is yet to be written to disk.
> if ((args & GET_BLOCK_NO_HOLE) && !PageUptodate(bh_result->b_page) ) {
> return -ENOENT ;
> }
> return 0 ; <- 0 retuns for IO_ERROR
> }
>
> Way around:
> test result of search_for_position_by_key
>
> Signed-off-by: Qu Fuping<[email protected]>
>
> Patch:
> diff -uNp /tmp/linux-2.6.12-rc6/fs/reiserfs/inode.c /tmp/linux-2.6.12-rc6.new/fs/reiserfs/inode.c
> --- /tmp/linux-2.6.12-rc6/fs/reiserfs/inode.c 2005-06-06 11:22:29.000000000 -0400
> +++ /tmp/linux-2.6.12-rc6.new/fs/reiserfs/inode.c 2005-06-15 13:56:45.552564512 -0400
> @@ -254,6 +254,7 @@ static int _get_block_create_0 (struct i
> char * p = NULL;
> int chars;
> int ret ;
> + int result ;
> int done = 0 ;
> unsigned long offset ;
>
> @@ -262,7 +263,8 @@ static int _get_block_create_0 (struct i
> (loff_t)block * inode->i_sb->s_blocksize + 1, TYPE_ANY, 3);
>
> research:
> - if (search_for_position_by_key (inode->i_sb, &key, &path) != POSITION_FOUND) {
> + result = search_for_position_by_key (inode->i_sb, &key, &path) ;
> + if (result != POSITION_FOUND) {
> pathrelse (&path);
> if (p)
> kunmap(bh_result->b_page) ;
> @@ -270,7 +272,8 @@ research:
> // That there is some MMAPED data associated with it that is yet to be written to disk.
> if ((args & GET_BLOCK_NO_HOLE) && !PageUptodate(bh_result->b_page) ) {
> return -ENOENT ;
> - }
> + }else if (result == IO_ERROR)
> + return -EIO ;
> return 0 ;
> }
>
Your patch is incomplete. There is one more search_for_position_by_key
at the end of this function. You probably want to check its return value
also.
>
>
-
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