Patch "xfs: Use xfs_icluster_size_fsb() to calculate inode chunk alignment" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

xfs: Use xfs_icluster_size_fsb() to calculate inode chunk alignment

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
xfs-use-xfs_icluster_size_fsb-to-calculate-inode-chunk-alignment.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Chandan Rajendra <[email protected]>
Date: Thu, 16 Feb 2017 17:12:16 -0800
Subject: xfs: Use xfs_icluster_size_fsb() to calculate inode chunk alignment

From: Chandan Rajendra <[email protected]>

commit 8ee9fdbebc84b39f1d1c201c5e32277c61d034aa upstream.

On a ppc64 system, executing generic/256 test with 32k block size gives the following call trace,

XFS: Assertion failed: args->maxlen > 0, file: /root/repos/linux/fs/xfs/libxfs/xfs_alloc.c, line: 2026

kernel BUG at /root/repos/linux/fs/xfs/xfs_message.c:113!

Oops: Exception in kernel mode, sig: 5 [#1]

SMP NR_CPUS=2048
DEBUG_PAGEALLOC
NUMA
pSeries

Modules linked in:
CPU: 2 PID: 19361 Comm: mkdir Not tainted 4.10.0-rc5 #58

task: c000000102606d80 task.stack: c0000001026b8000
NIP: c0000000004ef798 LR: c0000000004ef798 CTR: c00000000082b290
REGS: c0000001026bb090 TRAP: 0700 Not tainted (4.10.0-rc5)
MSR: 8000000000029032 <SF,EE,ME,IR,DR,RI>
CR: 28004428 XER: 00000000
CFAR: c0000000004ef180 SOFTE: 1
GPR00: c0000000004ef798 c0000001026bb310 c000000001157300 ffffffffffffffea
GPR04: 000000000000000a c0000001026bb130 0000000000000000 ffffffffffffffc0
GPR08: 00000000000000d1 0000000000000021 00000000ffffffd1 c000000000dd4990
GPR12: 0000000022004444 c00000000fe00800 0000000020000000 0000000000000000
GPR16: 0000000000000000 0000000043a606fc 0000000043a76c08 0000000043a1b3d0
GPR20: 000001002a35cd60 c0000001026bbb80 0000000000000000 0000000000000001
GPR24: 0000000000000240 0000000000000004 c00000062dc55000 0000000000000000
GPR28: 0000000000000004 c00000062ecd9200 0000000000000000 c0000001026bb6c0 NIP [c0000000004ef798] .assfail+0x28/0x30
LR [c0000000004ef798] .assfail+0x28/0x30

Call Trace:
[c0000001026bb310] [c0000000004ef798] .assfail+0x28/0x30 (unreliable)
[c0000001026bb380] [c000000000455d74] .xfs_alloc_space_available+0x194/0x1b0
[c0000001026bb410] [c00000000045b914] .xfs_alloc_fix_freelist+0x144/0x480
[c0000001026bb580] [c00000000045c368] .xfs_alloc_vextent+0x698/0xa90
[c0000001026bb650] [c0000000004a6200] .xfs_ialloc_ag_alloc+0x170/0x820
[c0000001026bb7c0] [c0000000004a9098] .xfs_dialloc+0x158/0x320
[c0000001026bb8a0] [c0000000004e628c] .xfs_ialloc+0x7c/0x610
[c0000001026bb990] [c0000000004e8138] .xfs_dir_ialloc+0xa8/0x2f0
[c0000001026bbaa0] [c0000000004e8814] .xfs_create+0x494/0x790
[c0000001026bbbf0] [c0000000004e5ebc] .xfs_generic_create+0x2bc/0x410
[c0000001026bbce0] [c0000000002b4a34] .vfs_mkdir+0x154/0x230
[c0000001026bbd70] [c0000000002bc444] .SyS_mkdirat+0x94/0x120
[c0000001026bbe30] [c00000000000b760] system_call+0x38/0xfc

Instruction dump:
4e800020 60000000 7c0802a6 7c862378 3c82ffca 7ca72b78 38841c18 7c651b78 38600000 f8010010 f821ff91 4bfff94d <0fe00000> 60000000 7c0802a6 7c892378

When block size is larger than inode cluster size, the call to XFS_B_TO_FSBT(mp, mp->m_inode_cluster_size) returns 0. Also, mkfs.xfs would have set xfs_sb->sb_inoalignmt to 0. This causes xfs_ialloc_cluster_alignment() to return 0. Due to this args.minalignslop (in xfs_ialloc_ag_alloc()) gets the unsigned equivalent of -1 assigned to it. This later causes alloc_len in xfs_alloc_space_available() to have a value of 0. In such a scenario when args.total is also 0, the assert statement "ASSERT(args->maxlen > 0);" fails.

This commit fixes the bug by replacing the call to XFS_B_TO_FSBT() in xfs_ialloc_cluster_alignment() with a call to xfs_icluster_size_fsb().

---
 fs/xfs/libxfs/xfs_ialloc.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

@@ -51,8 +51,7 @@ xfs_ialloc_cluster_alignment(
 	struct xfs_mount	*mp)
 {
 	if (xfs_sb_version_hasalign(&mp->m_sb) &&
-	    mp->m_sb.sb_inoalignmt >=
-			XFS_B_TO_FSBT(mp, mp->m_inode_cluster_size))
+	    mp->m_sb.sb_inoalignmt >= xfs_icluster_size_fsb(mp))
 		return mp->m_sb.sb_inoalignmt;
 	return 1;
 }

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/xfs-use-xfs_icluster_size_fsb-to-calculate-inode-chunk-alignment.patch queue-4.9/xfs-use-xfs_icluster_size_fsb-to-calculate-inode-alignment-mask.patch