From: Brian Foster Date: Thu, 12 Jul 2018 05:26:19 +0000 (-0700) Subject: xfs: allow null firstblock in xfs_bmapi_write() when tp is null X-Git-Tag: v4.19-rc1~175^2~108 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=3ae2d89174e4ba581093320afb48421ca95191d2;p=linux.git xfs: allow null firstblock in xfs_bmapi_write() when tp is null xfs_bmapi_write() always expects a valid firstblock pointer. It immediately dereferences the pointer to help determine how to initialize the bma.minleft field. The remaining accesses are related to modifying btree format forks, which is only relevant for !COW fork callers. The reflink code passes a NULL transaction to xfs_bmapi_write() in a couple places that do COW fork unwritten conversion. The purpose of the firstblock field is to track the first block allocation in the current transaction, so technically firstblock should not be required for these callers either. Tweak xfs_bmapi_write() to initialize the bma correctly without accessing the firstblock pointer if no transaction is provided in the first place. Update the reflink callers to pass NULL instead of otherwise unused firstblock references. Signed-off-by: Brian Foster Reviewed-by: Christoph Hellwig Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong --- diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c index dfff840c79f9..0b476a8e751c 100644 --- a/fs/xfs/libxfs/xfs_bmap.c +++ b/fs/xfs/libxfs/xfs_bmap.c @@ -4302,7 +4302,7 @@ xfs_bmapi_write( XFS_STATS_INC(mp, xs_blk_mapw); - if (*firstblock == NULLFSBLOCK) { + if (!tp || *firstblock == NULLFSBLOCK) { if (XFS_IFORK_FORMAT(ip, whichfork) == XFS_DINODE_FMT_BTREE) bma.minleft = be16_to_cpu(ifp->if_broot->bb_level) + 1; else diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c index bef780171962..b1bc2eb54a14 100644 --- a/fs/xfs/xfs_reflink.c +++ b/fs/xfs/xfs_reflink.c @@ -314,7 +314,6 @@ xfs_reflink_convert_cow_extent( xfs_fileoff_t offset_fsb, xfs_filblks_t count_fsb) { - xfs_fsblock_t first_block = NULLFSBLOCK; int nimaps = 1; if (imap->br_state == XFS_EXT_NORM) @@ -325,8 +324,8 @@ xfs_reflink_convert_cow_extent( if (imap->br_blockcount == 0) return 0; return xfs_bmapi_write(NULL, ip, imap->br_startoff, imap->br_blockcount, - XFS_BMAPI_COWFORK | XFS_BMAPI_CONVERT, &first_block, - 0, imap, &nimaps); + XFS_BMAPI_COWFORK | XFS_BMAPI_CONVERT, NULL, 0, imap, + &nimaps); } /* Convert all of the unwritten CoW extents in a file's range to real ones. */ @@ -341,7 +340,6 @@ xfs_reflink_convert_cow( xfs_fileoff_t end_fsb = XFS_B_TO_FSB(mp, offset + count); xfs_filblks_t count_fsb = end_fsb - offset_fsb; struct xfs_bmbt_irec imap; - xfs_fsblock_t first_block = NULLFSBLOCK; int nimaps = 1, error = 0; ASSERT(count != 0); @@ -349,8 +347,7 @@ xfs_reflink_convert_cow( xfs_ilock(ip, XFS_ILOCK_EXCL); error = xfs_bmapi_write(NULL, ip, offset_fsb, count_fsb, XFS_BMAPI_COWFORK | XFS_BMAPI_CONVERT | - XFS_BMAPI_CONVERT_ONLY, &first_block, 0, &imap, - &nimaps); + XFS_BMAPI_CONVERT_ONLY, NULL, 0, &imap, &nimaps); xfs_iunlock(ip, XFS_ILOCK_EXCL); return error; }