From mboxrd@z Thu Jan 1 00:00:00 1970 From: fs Subject: [PATCH][RESEND] ReiserFS file.c several bug-fix Date: Mon, 27 Jun 2005 16:09:56 -0400 Message-ID: <1119902996.2851.16.camel@CoolQ> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="=-R9DXeoJeDwc0x6F0DTBv" Cc: linux-fsdevel , Hans Reiser , Vladimir Saveliev , iscas-linaccident Return-path: list-help: list-unsubscribe: list-post: Errors-To: flx@namesys.com To: reiserfs-list List-Id: linux-fsdevel.vger.kernel.org --=-R9DXeoJeDwc0x6F0DTBv Content-Type: text/plain Content-Transfer-Encoding: 7bit Related FS: ReiserFS Related Files: fs/reiserfs/file.c Bug description: Make a ReiserFS partition in USB storage HDD, create a test file with enough size(dd if=/dev/zero of=testfile bs=4096 count=1024). Write a program, do: int fd; char buf[4096]; fd = open("testfile", O_RDWRO | O_CREAT | O_SYNC, (S_IRWXU | S_IRWXG | S_IRWXO) ); or open("testfile", O_RDWRO | O_CREAT | O_DSYNC, (S_IRWXU | S_IRWXG | S_IRWXO) ); write(fd, buf, sizeof(buf)); close(fd); After each operation, pause for a while, such as 3s. Between open and write, unlug the USB wire. write returns no error instead of -EIO . Bug analysis: reiserfs_file_write will claim some blocks, commit the I/O request, if O_SYNC and O_DSYNC is used, it will if ((file->f_flags & O_SYNC) || IS_SYNC(inode)) res = generic_osync_inode(inode, file->f_mapping, OSYNC_METADATA|OSYNC_DATA); The question is, if I/O error occurs, res = reiserfs_allocate_blocks_for_region fails with -EIO, so it will exit the loop, no I/O request, no page marked as dirty. If generic_osync_inode runs, it returns 0(no dirty page), res will be overwritten from -EIO to 0, thus no error report. Also, reiserfs_file_write contains a serious bug, see here blocks_to_allocate = reiserfs_prepare_file_region_for_write (inode, pos, num_pages, write_bytes, prepared_pages); Here blocks_to_allocate is defined as size_t, i.e. unsigned int, but reiserfs_prepare_file_region_for_write is declared as int, so sometimes it will return -EIO, -ENOENT, etc, take a look at this line if ( blocks_to_allocate < 0 ) { <- This will never happen res = blocks_to_allocate; reiserfs_release_claimed_blocks(inode->i_sb, num_pages << (PAGE_CACHE_SHIFT - inode->i_blkbits)); break; } Way around: 1) if already_written is zero, don't do generic_osync_inode 2) tell the result of reiserfs_prepare_file_region_for_write with IS_ERR macro or cast it to size_t Signed-off-by: Qu Fuping Patch: diff -uNp linux-2.6.12/fs/reiserfs/file.c linux-2.6.12-new/fs/reiserfs/file.c --=-R9DXeoJeDwc0x6F0DTBv Content-Disposition: attachment; filename=reiserfs_write.diff Content-Type: text/x-patch; name=reiserfs_write.diff; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit --- linux-2.6.12/fs/reiserfs/file.c 2005-06-23 14:59:27.000000000 -0400 +++ linux-2.6.12-new/fs/reiserfs/file.c 2005-06-23 15:34:49.000000000 -0400 @@ -1306,7 +1306,7 @@ static ssize_t reiserfs_file_write( stru so that nobody else can access these until we are done. We get number of actual blocks needed as a result.*/ blocks_to_allocate = reiserfs_prepare_file_region_for_write(inode, pos, num_pages, write_bytes, prepared_pages); - if ( blocks_to_allocate < 0 ) { + if ( IS_ERROR((const void *)blocks_to_allocate) ) { res = blocks_to_allocate; reiserfs_release_claimed_blocks(inode->i_sb, num_pages << (PAGE_CACHE_SHIFT - inode->i_blkbits)); break; @@ -1363,6 +1363,10 @@ static ssize_t reiserfs_file_write( stru } } + /* If nothing is written, no need(actually, mustn't) to sync pages, just return res */ + if( already_written == 0 ) + goto out; + if ((file->f_flags & O_SYNC) || IS_SYNC(inode)) res = generic_osync_inode(inode, file->f_mapping, OSYNC_METADATA|OSYNC_DATA); --=-R9DXeoJeDwc0x6F0DTBv--