From: Dave Chinner <dchinner@xxxxxxxxxx> This results in BMBT corruption, as seen by this test: # mkfs.xfs -f -d size=40051712b,agcount=4 /dev/vdc .... # mount /dev/vdc /mnt/scratch # xfs_io -ft -c "extsize 16m" -c "falloc 0 30g" -c "bmap -vp" /mnt/scratch/foo which results in this failure on a debug kernel: XFS: Assertion failed: (blockcount & xfs_mask64hi(64-BMBT_BLOCKCOUNT_BITLEN)) == 0, file: fs/xfs/libxfs/xfs_bmap_btree.c, line: 211 .... Call Trace: [<ffffffff814cf0ff>] xfs_bmbt_set_allf+0x8f/0x100 [<ffffffff814cf18d>] xfs_bmbt_set_all+0x1d/0x20 [<ffffffff814f2efe>] xfs_iext_insert+0x9e/0x120 [<ffffffff814c7956>] ? xfs_bmap_add_extent_hole_real+0x1c6/0xc70 [<ffffffff814c7956>] xfs_bmap_add_extent_hole_real+0x1c6/0xc70 [<ffffffff814caaab>] xfs_bmapi_write+0x72b/0xed0 [<ffffffff811c72ac>] ? kmem_cache_alloc+0x15c/0x170 [<ffffffff814fe070>] xfs_alloc_file_space+0x160/0x400 [<ffffffff81ddcc29>] ? down_write+0x29/0x60 [<ffffffff815063eb>] xfs_file_fallocate+0x29b/0x310 [<ffffffff811d2bc8>] ? __sb_start_write+0x58/0x120 [<ffffffff811e3e18>] ? do_vfs_ioctl+0x318/0x570 [<ffffffff811cd680>] vfs_fallocate+0x140/0x260 [<ffffffff811ce6f8>] SyS_fallocate+0x48/0x80 [<ffffffff81ddec09>] system_call_fastpath+0x12/0x17 The tracepoint that indicates the extent that triggered the assert failure is: xfs_iext_insert: idx 0 offset 0 block 16777224 count 2097152 flag 1 Clearly indicating that the extent length is greater than MAXEXTLEN, which is 2097151. A prior trace point shows the allocation was an exact size match and that a length greater than MAXEXTLEN was asked for: xfs_alloc_size_done: agno 1 agbno 8 minlen 2097152 maxlen 2097152 ^^^^^^^ ^^^^^^^ The issue is that the extent size hint alignment is rounding up the extent size past MAXEXTLEN, because xfs_bmapi_write() is not taking into account extent size hints when calculating the maximum extent length to allocate. xfs_bmapi_reserve_delalloc() is already doing this, but direct extent allocation is not. We don't see this problem with extent size hints through the IO path because we can't do single IOs large enough to trigger MAXEXTLEN allocation. fallocate(), OTOH, is not limited in it's allocation sizes and so needs help here. The fix is simply to copy the logic from xfs_bmapi_reserve_delalloc() and apply it apropriately to xfs_bmapi_write(). I also add an ASSERT() to xfs_bmap_extsize_align() so we'll catch cases of alignment exceeding MAXEXTLEN on debug kernel machines in future. Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx> --- fs/xfs/libxfs/xfs_bmap.c | 51 +++++++++++++++++++++++++++++++++++------------- 1 file changed, 37 insertions(+), 14 deletions(-) diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c index aeffeaa..37949b5 100644 --- a/fs/xfs/libxfs/xfs_bmap.c +++ b/fs/xfs/libxfs/xfs_bmap.c @@ -3224,12 +3224,21 @@ xfs_bmap_extsize_align( align_alen += temp; align_off -= temp; } + + /* Same adjustment for the end of the requested area. */ + temp = (align_alen % extsz); + if (temp) + align_alen += extsz - temp; + /* - * Same adjustment for the end of the requested area. + * we are in trouble if the caller requested an extent that will align + * to something larger than the supported on disk extent size. Assert + * fail here to catch callers that make this mistake; they should always + * be setting the maximum allocation length to be (MAXEXTLEN - extsz) so + * we can round outwards here for alignment. */ - if ((temp = (align_alen % extsz))) { - align_alen += extsz - temp; - } + ASSERT(align_alen <= MAXEXTLEN); + /* * If the previous block overlaps with this proposed allocation * then move the start forward without adjusting the length. @@ -4074,6 +4083,27 @@ xfs_bmapi_read( return 0; } +/* + * Calculate the maximum extent length we can ask to allocate after taking into + * account the on-disk size limitations, the extent size hints and the size + * being requested. We have to deal with the extent size hint here because the + * allocation will attempt alignment and hence grow the length outwards by up to + * @extsz on either side. + */ +static inline xfs_extlen_t +xfs_bmapi_max_extlen( + struct xfs_inode *ip, + xfs_extlen_t length) +{ + xfs_extlen_t extsz = xfs_get_extsz_hint(ip); + xfs_extlen_t max_length = MAXEXTLEN; + + if (extsz) + max_length -= 2 * extsz - 1; + + return (length < max_length) ? length : max_length; +} + STATIC int xfs_bmapi_reserve_delalloc( struct xfs_inode *ip, @@ -4092,20 +4122,13 @@ xfs_bmapi_reserve_delalloc( xfs_extlen_t extsz; int error; - alen = XFS_FILBLKS_MIN(len, MAXEXTLEN); + alen = xfs_bmapi_max_extlen(ip, len); if (!eof) alen = XFS_FILBLKS_MIN(alen, got->br_startoff - aoff); - /* Figure out the extent size, adjust alen */ + /* Figure out the extent size, align alen */ extsz = xfs_get_extsz_hint(ip); if (extsz) { - /* - * Make sure we don't exceed a single extent length when we - * align the extent by reducing length we are going to - * allocate by the maximum amount extent size aligment may - * require. - */ - alen = XFS_FILBLKS_MIN(len, MAXEXTLEN - (2 * extsz - 1)); error = xfs_bmap_extsize_align(mp, got, prev, extsz, rt, eof, 1, 0, &aoff, &alen); ASSERT(!error); @@ -4287,7 +4310,7 @@ xfs_bmapi_allocate( &bma->prev); } } else { - bma->length = XFS_FILBLKS_MIN(bma->length, MAXEXTLEN); + bma->length = xfs_bmapi_max_extlen(bma->ip, bma->length); if (!bma->eof) bma->length = XFS_FILBLKS_MIN(bma->length, bma->got.br_startoff - bma->offset); -- 2.0.0 _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs