linux.git/fs/dax.c, branch v6.3

fsdax: force clear dirty mark if CoW

2023-04-06T01:06:23+00:00

XFS allows CoW on non-shared extents to combat fragmentation[1].  The old
non-shared extent could be mwrited before, its dax entry is marked dirty. 

This results in a WARNing:

[   28.512349] ------------[ cut here ]------------
[   28.512622] WARNING: CPU: 2 PID: 5255 at fs/dax.c:390 dax_insert_entry+0x342/0x390
[   28.513050] Modules linked in: rpcsec_gss_krb5 auth_rpcgss nfsv4 nfs lockd grace fscache netfs nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 ip_set nf_tables
[   28.515462] CPU: 2 PID: 5255 Comm: fsstress Kdump: loaded Not tainted 6.3.0-rc1-00001-g85e1481e19c1-dirty #117
[   28.515902] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS Arch Linux 1.16.1-1-1 04/01/2014
[   28.516307] RIP: 0010:dax_insert_entry+0x342/0x390
[   28.516536] Code: 30 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc 48 8b 45 20 48 83 c0 01 e9 e2 fe ff ff 48 8b 45 20 48 83 c0 01 e9 cd fe ff ff <0f> 0b e9 53 ff ff ff 48 8b 7c 24 08 31 f6 e8 1b 61 a1 00 eb 8c 48
[   28.517417] RSP: 0000:ffffc9000845fb18 EFLAGS: 00010086
[   28.517721] RAX: 0000000000000053 RBX: 0000000000000155 RCX: 000000000018824b
[   28.518113] RDX: 0000000000000000 RSI: ffffffff827525a6 RDI: 00000000ffffffff
[   28.518515] RBP: ffffea00062092c0 R08: 0000000000000000 R09: ffffc9000845f9c8
[   28.518905] R10: 0000000000000003 R11: ffffffff82ddb7e8 R12: 0000000000000155
[   28.519301] R13: 0000000000000000 R14: 000000000018824b R15: ffff88810cfa76b8
[   28.519703] FS:  00007f14a0c94740(0000) GS:ffff88817bd00000(0000) knlGS:0000000000000000
[   28.520148] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   28.520472] CR2: 00007f14a0c8d000 CR3: 000000010321c004 CR4: 0000000000770ee0
[   28.520863] PKRU: 55555554
[   28.521043] Call Trace:
[   28.521219]  
[   28.521368]  dax_fault_iter+0x196/0x390
[   28.521595]  dax_iomap_pte_fault+0x19b/0x3d0
[   28.521852]  __xfs_filemap_fault+0x234/0x2b0
[   28.522116]  __do_fault+0x30/0x130
[   28.522334]  do_fault+0x193/0x340
[   28.522586]  __handle_mm_fault+0x2d3/0x690
[   28.522975]  handle_mm_fault+0xe6/0x2c0
[   28.523259]  do_user_addr_fault+0x1bc/0x6f0
[   28.523521]  exc_page_fault+0x60/0x140
[   28.523763]  asm_exc_page_fault+0x22/0x30
[   28.524001] RIP: 0033:0x7f14a0b589ca
[   28.524225] Code: c5 fe 7f 07 c5 fe 7f 47 20 c5 fe 7f 47 40 c5 fe 7f 47 60 c5 f8 77 c3 66 0f 1f 84 00 00 00 00 00 40 0f b6 c6 48 89 d1 48 89 fa  aa 48 89 d0 c5 f8 77 c3 66 66 2e 0f 1f 84 00 00 00 00 00 66 90
[   28.525198] RSP: 002b:00007fff1dea1c98 EFLAGS: 00010202
[   28.525505] RAX: 000000000000001e RBX: 000000000014a000 RCX: 0000000000006046
[   28.525895] RDX: 00007f14a0c82000 RSI: 000000000000001e RDI: 00007f14a0c8d000
[   28.526290] RBP: 000000000000006f R08: 0000000000000004 R09: 000000000014a000
[   28.526681] R10: 0000000000000008 R11: 0000000000000246 R12: 028f5c28f5c28f5c
[   28.527067] R13: 8f5c28f5c28f5c29 R14: 0000000000011046 R15: 00007f14a0c946c0
[   28.527449]  
[   28.527600] ---[ end trace 0000000000000000 ]---


To be able to delete this entry, clear its dirty mark before
invalidate_inode_pages2_range().

[1] https://lore.kernel.org/linux-xfs/20230321151339.GA11376@frogsfrogsfrogs/

Link: https://lkml.kernel.org/r/1679653680-2-1-git-send-email-ruansy.fnst@fujitsu.com
Fixes: f80e1668888f3 ("fsdax: invalidate pages when CoW")
Signed-off-by: Shiyang Ruan 
Cc: Dan Williams 
Cc: Darrick J. Wong 
Cc: Jan Kara 
Cc: Matthew Wilcox (Oracle) 
Cc: 
Signed-off-by: Andrew Morton

fsdax: dedupe should compare the min of two iters' length

2023-03-28T22:24:32+00:00

In an dedupe comparison iter loop, the length of iomap_iter decreases
because it implies the remaining length after each iteration.

The dedupe command will fail with -EIO if the range is larger than one 
page size and not aligned to the page size.  Also report warning in dmesg:

[ 4338.498374] ------------[ cut here ]------------
[ 4338.498689] WARNING: CPU: 3 PID: 1415645 at fs/iomap/iter.c:16 
...

The compare function should use the min length of the current iters,
not the total length.

Link: https://lkml.kernel.org/r/1679469958-2-1-git-send-email-ruansy.fnst@fujitsu.com
Fixes: 0e79e3736d54 ("fsdax: dedupe: iter two files at the same time")
Signed-off-by: Shiyang Ruan 
Reviewed-by: Darrick J. Wong 
Cc: Dan Williams 
Cc: Jan Kara 
Cc: Matthew Wilcox (Oracle) 
Cc: 
Signed-off-by: Andrew Morton

fsdax: unshare: zero destination if srcmap is HOLE or UNWRITTEN

2023-03-28T22:24:32+00:00

unshare copies data from source to destination.  But if the source is
HOLE or UNWRITTEN extents, we should zero the destination, otherwise
the HOLE or UNWRITTEN part will be user-visible old data of the new
allocated extent.

Found by running generic/649 while mounting with -o dax=always on pmem.

Link: https://lkml.kernel.org/r/1679483469-2-1-git-send-email-ruansy.fnst@fujitsu.com
Fixes: d984648e428b ("fsdax,xfs: port unshare to fsdax")
Signed-off-by: Shiyang Ruan 
Cc: Dan Williams 
Cc: Darrick J. Wong 
Cc: Jan Kara 
Cc: Matthew Wilcox (Oracle) 
Cc: Alistair Popple 
Cc: Jason Gunthorpe 
Cc: John Hubbard 
Cc: 
Signed-off-by: Andrew Morton

fsdax: dax_unshare_iter() should return a valid length

2023-02-04T01:52:24+00:00

The copy_mc_to_kernel() will return 0 if it executed successfully.  Then
the return value should be set to the length it copied.

[akpm@linux-foundation.org: don't mess up `ret', per Matthew]
Link: https://lkml.kernel.org/r/1675341227-14-1-git-send-email-ruansy.fnst@fujitsu.com
Fixes: d984648e428b ("fsdax,xfs: port unshare to fsdax")
Signed-off-by: Shiyang Ruan 
Cc: Darrick J. Wong 
Cc: Alistair Popple 
Cc: Dan Williams 
Cc: Dave Chinner 
Cc: Jason Gunthorpe 
Cc: John Hubbard 
Cc: Matthew Wilcox 
Signed-off-by: Andrew Morton

fsdax,xfs: port unshare to fsdax

2022-12-12T02:12:17+00:00

Implement unshare in fsdax mode: copy data from srcmap to iomap.

Link: https://lkml.kernel.org/r/1669908753-169-1-git-send-email-ruansy.fnst@fujitsu.com
Signed-off-by: Shiyang Ruan 
Reviewed-by: Darrick J. Wong 
Cc: Alistair Popple 
Cc: Dan Williams 
Cc: Dave Chinner 
Cc: Jason Gunthorpe 
Cc: John Hubbard 
Signed-off-by: Andrew Morton

fsdax: dedupe: iter two files at the same time

2022-12-12T02:12:16+00:00

The iomap_iter() on a range of one file may loop more than once.  In this
case, the inner dst_iter can update its iomap but the outer src_iter
can't.  This may cause the wrong remapping in filesystem.  Let them called
at the same time.

Link: https://lkml.kernel.org/r/1669908701-93-1-git-send-email-ruansy.fnst@fujitsu.com
Signed-off-by: Shiyang Ruan 
Reviewed-by: Darrick J. Wong 
Cc: Alistair Popple 
Cc: Dan Williams 
Cc: Dave Chinner 
Cc: Jason Gunthorpe 
Cc: John Hubbard 
Signed-off-by: Andrew Morton

fsdax,xfs: set the shared flag when file extent is shared

2022-12-12T02:12:16+00:00

If a dax page is shared, mapread at different offsets can also trigger
page fault on same dax page.  So, change the flag from "cow" to "shared". 
And get the shared flag from filesystem when read.

Link: https://lkml.kernel.org/r/1669908538-55-5-git-send-email-ruansy.fnst@fujitsu.com
Signed-off-by: Shiyang Ruan 
Reviewed-by: Darrick J. Wong 
Cc: Alistair Popple 
Cc: Dan Williams 
Cc: Dave Chinner 
Cc: Jason Gunthorpe 
Cc: John Hubbard 
Signed-off-by: Andrew Morton

fsdax: zero the edges if source is HOLE or UNWRITTEN

2022-12-12T02:12:16+00:00

If srcmap contains invalid data, such as HOLE and UNWRITTEN, the dest page
should be zeroed.  Otherwise, since it's a pmem, old data may remains on
the dest page, the result of CoW will be incorrect.

The function name is also not easy to understand, rename it to
"dax_iomap_copy_around()", which means it copies data around the range.

[akpm@linux-foundation.org: update dax_iomap_copy_around() kerneldoc, per Darrick]
Link: https://lkml.kernel.org/r/1669973145-318-1-git-send-email-ruansy.fnst@fujitsu.com
Link: https://lkml.kernel.org/r/1669908538-55-4-git-send-email-ruansy.fnst@fujitsu.com
Signed-off-by: Shiyang Ruan 
Reviewed-by: Darrick J. Wong 
Reviewed-by: Allison Henderson 
Cc: Alistair Popple 
Cc: Dan Williams 
Cc: Dave Chinner 
Cc: Jason Gunthorpe 
Cc: John Hubbard 
Signed-off-by: Andrew Morton

fsdax: invalidate pages when CoW

2022-12-12T02:12:16+00:00

CoW changes the share state of a dax page, but the share count of the page
isn't updated.  The next time access this page, it should have been a
newly accessed, but old association exists.  So, we need to clear the
share state when CoW happens, in both dax_iomap_rw() and dax_zero_iter().

Link: https://lkml.kernel.org/r/1669908538-55-3-git-send-email-ruansy.fnst@fujitsu.com
Signed-off-by: Shiyang Ruan 
Reviewed-by: Darrick J. Wong 
Cc: Alistair Popple 
Cc: Dan Williams 
Cc: Dave Chinner 
Cc: Jason Gunthorpe 
Cc: John Hubbard 
Signed-off-by: Andrew Morton

fsdax: introduce page->share for fsdax in reflink mode

2022-12-12T02:12:15+00:00

Patch series "fsdax,xfs: fix warning messages", v2.

Many testcases failed in dax+reflink mode with warning message in dmesg.
Such as generic/051,075,127.  The warning message is like this:
[  775.509337] ------------[ cut here ]------------
[  775.509636] WARNING: CPU: 1 PID: 16815 at fs/dax.c:386 dax_insert_entry.cold+0x2e/0x69
[  775.510151] Modules linked in: auth_rpcgss oid_registry nfsv4 algif_hash af_alg af_packet nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat iptable_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 ip_set nf_tables nfnetlink ip6table_filter ip6_tables iptable_filter ip_tables x_tables dax_pmem nd_pmem nd_btt sch_fq_codel configfs xfs libcrc32c fuse
[  775.524288] CPU: 1 PID: 16815 Comm: fsx Kdump: loaded Tainted: G        W          6.1.0-rc4+ #164 eb34e4ee4200c7cbbb47de2b1892c5a3e027fd6d
[  775.524904] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS Arch Linux 1.16.0-3-3 04/01/2014
[  775.525460] RIP: 0010:dax_insert_entry.cold+0x2e/0x69
[  775.525797] Code: c7 c7 18 eb e0 81 48 89 4c 24 20 48 89 54 24 10 e8 73 6d ff ff 48 83 7d 18 00 48 8b 54 24 10 48 8b 4c 24 20 0f 84 e3 e9 b9 ff <0f> 0b e9 dc e9 b9 ff 48 c7 c6 a0 20 c3 81 48 c7 c7 f0 ea e0 81 48
[  775.526708] RSP: 0000:ffffc90001d57b30 EFLAGS: 00010082
[  775.527042] RAX: 000000000000002a RBX: 0000000000000000 RCX: 0000000000000042
[  775.527396] RDX: ffffea000a0f6c80 RSI: ffffffff81dfab1b RDI: 00000000ffffffff
[  775.527819] RBP: ffffea000a0f6c40 R08: 0000000000000000 R09: ffffffff820625e0
[  775.528241] R10: ffffc90001d579d8 R11: ffffffff820d2628 R12: ffff88815fc98320
[  775.528598] R13: ffffc90001d57c18 R14: 0000000000000000 R15: 0000000000000001
[  775.528997] FS:  00007f39fc75d740(0000) GS:ffff88817bc80000(0000) knlGS:0000000000000000
[  775.529474] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  775.529800] CR2: 00007f39fc772040 CR3: 0000000107eb6001 CR4: 00000000003706e0
[  775.530214] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  775.530592] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  775.531002] Call Trace:
[  775.531230]  
[  775.531444]  dax_fault_iter+0x267/0x6c0
[  775.531719]  dax_iomap_pte_fault+0x198/0x3d0
[  775.532002]  __xfs_filemap_fault+0x24a/0x2d0 [xfs aa8d25411432b306d9554da38096f4ebb86bdfe7]
[  775.532603]  __do_fault+0x30/0x1e0
[  775.532903]  do_fault+0x314/0x6c0
[  775.533166]  __handle_mm_fault+0x646/0x1250
[  775.533480]  handle_mm_fault+0xc1/0x230
[  775.533810]  do_user_addr_fault+0x1ac/0x610
[  775.534110]  exc_page_fault+0x63/0x140
[  775.534389]  asm_exc_page_fault+0x22/0x30
[  775.534678] RIP: 0033:0x7f39fc55820a
[  775.534950] Code: 00 01 00 00 00 74 99 83 f9 c0 0f 87 7b fe ff ff c5 fe 6f 4e 20 48 29 fe 48 83 c7 3f 49 8d 0c 10 48 83 e7 c0 48 01 fe 48 29 f9  a4 c4 c1 7e 7f 00 c4 c1 7e 7f 48 20 c5 f8 77 c3 0f 1f 44 00 00
[  775.535839] RSP: 002b:00007ffc66a08118 EFLAGS: 00010202
[  775.536157] RAX: 00007f39fc772001 RBX: 0000000000042001 RCX: 00000000000063c1
[  775.536537] RDX: 0000000000006400 RSI: 00007f39fac42050 RDI: 00007f39fc772040
[  775.536919] RBP: 0000000000006400 R08: 00007f39fc772001 R09: 0000000000042000
[  775.537304] R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000001
[  775.537694] R13: 00007f39fc772000 R14: 0000000000006401 R15: 0000000000000003
[  775.538086]  
[  775.538333] ---[ end trace 0000000000000000 ]---

This also affects dax+noreflink mode if we run the test after a
dax+reflink test.  So, the most urgent thing is solving the warning
messages.

With these fixes, most warning messages in dax_associate_entry() are gone.
But honestly, generic/388 will randomly failed with the warning.  The
case shutdown the xfs when fsstress is running, and do it for many times. 
I think the reason is that dax pages in use are not able to be invalidated
in time when fs is shutdown.  The next time dax page to be associated, it
still remains the mapping value set last time.  I'll keep on solving it.

The warning message in dax_writeback_one() can also be fixed because of
the dax unshare.


This patch (of 8):

fsdax page is used not only when CoW, but also mapread.  To make the it
easily understood, use 'share' to indicate that the dax page is shared by
more than one extent.  And add helper functions to use it.

Also, the flag needs to be renamed to PAGE_MAPPING_DAX_SHARED.

[ruansy.fnst@fujitsu.com: rename several functions]
  Link: https://lkml.kernel.org/r/1669972991-246-1-git-send-email-ruansy.fnst@fujitsu.com
[ruansy.fnst@fujitsu.com: v2.2]
  Link: https://lkml.kernel.org/r/1670381359-53-1-git-send-email-ruansy.fnst@fujitsu.com
Link: https://lkml.kernel.org/r/1669908538-55-1-git-send-email-ruansy.fnst@fujitsu.com
Link: https://lkml.kernel.org/r/1669908538-55-2-git-send-email-ruansy.fnst@fujitsu.com
Signed-off-by: Shiyang Ruan 
Reviewed-by: Allison Henderson 
Reviewed-by: Darrick J. Wong 
Cc: Dan Williams 
Cc: Dave Chinner 
Cc: Jason Gunthorpe 
Cc: Alistair Popple 
Cc: John Hubbard 
Signed-off-by: Andrew Morton