On Mon, 25 Mar 2024, NeilBrown wrote: > With two clients, each with NFSv3 mounts of the same directory, the sequence: > > client1 client2 > ls -l afile > echo hello there > afile > echo HELLO > afile > cat afile > > will show > HELLO > there > > because the O_TRUNC requested in the final 'echo' doesn't take effect. > This is because the "Negative dentry, just create a file" section in > lookup_open() assumes that the file *does* get created since the dentry > was negative, so it sets FMODE_CREATED, and this causes do_open() to > clear O_TRUNC and so the file doesn't get truncated. > > Even mounting with -o lookupcache=none does not help as > nfs_neg_need_reval() always returns false if LOOKUP_CREATE is set. > > This patch fixes the problem by providing an atomic_open inode operation > for NFSv3 (and v2). The code is largely the code from the branch in > lookup_open() when atomic_open is not provided. The significant change > is that the O_TRUNC flag is passed a new nfs_do_create() which add > 'trunc' handling to nfs_create(). > > With this change we also optimise away an unnecessary LOOKUP before the > file is created. > Hi Neil, There's an LTP test failure that Aishwarya bisected back to this patch. Possibly because the new function doesn't check the max filename length before hitting this warning in encode_filename3(): WARN_ON_ONCE(length > NFS3_MAXNAMLEN); I saw some old commit message that mentioned callers should be checking it, so it seems like a plausible bisect because the test is testing invalid name lengths. But I didn't look in any more detail than that. statvfs01 and inotify02 tests are failing. The full output is at the end. Thanks James statvfs01.c:32: TPASS: statvfs(TEST_PATH, &buf) p<4>[ 7735.368939] ------------[ cut here ]------------ assed <4>[ 7735.376605] WARNING: CPU: 3 PID: 387286 at fs/nfs/nfs3xdr.c:188 encode_filename3+0x44/0x4c statvfs01.c:44: TPASS: creat(vali<4>[ 7735.385773] Modules linked in: quota_v2 quota_tree dummy veth overlay binfmt_misc btrfs blake2b_generic libcrc32c xor xor_neon raid6_pq zstd_compress fuse drm backlight ip_tables x_tables ipv6 crct10dif_ce onboard_usb_dev smsc [last unloaded: binfmt_misc] d_fname, 0444) returned fd 3<4>[ 7735.411537] CPU: 3 PID: 387286 Comm: statvfs01 Not tainted 6.9.0-next-20240523 #1 <4>[ 7735.421719] Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Platform, BIOS EDK II Jan 30 2024 <4>[ 7735.432948] pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) <4>[ 7735.440191] pc : encode_filename3+0x44/0x4c <4>[ 7735.444650] lr : nfs3_xdr_enc_create3args+0x44/0xf8 <4>[ 7735.449807] sp : ffff800088703800 <4>[ 7735.453386] x29: ffff800088703800 x28: ffff8000826b6388 x27: ffff800088703c70 <4>[ 7735.460812] x26: ffff00082752f780 x25: 0000000000000001 x24: 0000000000440040 <4>[ 7735.468238] x23: 0000000000000100 x22: ffff000827520010 x21: ffff00082712b600 <4>[ 7735.475663] x20: ffff000827520010 x19: 0000000000000100 x18: 0000000000000000 <4>[ 7735.483088] x17: 0000000000000000 x16: 0000000000000000 x15: 6262626262626262 <4>[ 7735.490512] x14: 6262626262626262 x13: 14269a2303320025 x12: 43956040606e0dbf <4>[ 7735.497937] x11: ce4b9be95ac6e1de x10: 00000000017009cd x9 : 0332002543956040 <4>[ 7735.505362] x8 : 606e0dbfce4b9be9 x7 : 5ac6e1de00000000 x6 : 017009cd01070001 <4>[ 7735.512786] x5 : ffff00082589b87c x4 : ffff00082410216e x3 : ffff800080445400 <4>[ 7735.520211] x2 : 0000000000000100 x1 : ffff000827520010 x0 : ffff8000887038b8 <4>[ 7735.527636] Call trace: <4>[ 7735.530345] encode_filename3+0x44/0x4c <4>[ 7735.534457] nfs3_xdr_enc_create3args+0x44/0xf8 <4>[ 7735.539264] rpcauth_wrap_req_encode+0x1c/0x2c <4>[ 7735.543986] rpcauth_wrap_req+0x20/0x2c <4>[ 7735.548097] call_encode+0x114/0x294 <4>[ 7735.551947] __rpc_execute+0xb0/0x3a0 <4>[ 7735.555883] rpc_execute+0x9c/0xbc <4>[ 7735.559557] rpc_run_task+0x128/0x1cc <4>[ 7735.563494] rpc_call_sync+0x58/0xb8 <4>[ 7735.567343] nfs3_rpc_wrapper+0x3c/0x84 <4>[ 7735.571454] nfs3_proc_create+0xb0/0x2cc <4>[ 7735.575651] nfs_atomic_open_v23+0xfc/0x14c <4>[ 7735.580107] path_openat+0x64c/0xee0 <4>[ 7735.583957] do_filp_open+0x80/0x12c <4>[ 7735.587806] do_sys_openat2+0xb4/0xe8 <4>[ 7735.591739] __arm64_sys_openat+0x64/0xac <4>[ 7735.596021] invoke_syscall+0x48/0x118 <4>[ 7735.600047] el0_svc_common.constprop.0+0x40/0xe0 <4>[ 7735.605029] do_el0_svc+0x1c/0x28 <4>[ 7735.608617] el0_svc+0x34/0xdc <4>[ 7735.611944] el0t_64_sync_handler+0xc0/0xc4 <4>[ 7735.616404] el0t_64_sync+0x190/0x194 <4>[ 7735.620339] ---[ end trace 0000000000000000 ]--- statvfs01.c:48: TFAIL: creat(toolong_fname, 0444) expected ENAMETOOLONG: EIO (5) <6>[ 7735.689265] EXT4-fs (loop0): unmounting filesystem 99c92af1-0341-4dd6-920c-bc7461170ff2. tst_test.c:1650: TINFO: === Testing on ext3 === tst_test.c:1105: TINFO: Formatting /dev/loop0 with ext3 opts='' extra opts='' mke2fs 1.46.2 (28-Feb-2021) tst_test.c:1119: TINFO: Mounting /<6>[ 7737.794577] EXT4-fs (loop0): mounting ext3 file system using the ext4 subsystem dev/loop0 to /ltp-tmp/ltp-aTUvKrI1Ui/LTP_stakwdpzv/mntpoint fstyp=ext3 flags=0 <6>[ 7737.818721] EXT4-fs (loop0): mounted filesystem 91699e00-ff2a-49b3-8159-38ae80bdd87d r/w with ordered data mode. Quota mode: none. <4>[ 7737.830824] ext3 filesystem being mounted at /ltp-tmp/ltp-aTUvKrI1Ui/LTP_stakwdpzv/mntpoint supports timestamps until 2038-01-19 (0x7fffffff) statvfs01.c:32: TPASS: statvfs(TEST_PATH, &buf) passed statvfs01.c:44: TPASS: creat(valid_fname, 0444) returned fd 3 statvfs01.c:48: TFAIL: creat(toolong_fname, 0444) expected ENAMETOOLON<6>[ 7737.861118] EXT4-fs (loop0): unmounting filesystem 91699e00-ff2a-49b3-8159-38ae80bdd87d. G: EIO (5) tst_test.c:1650: TINFO: === Testing on ext4 === tst_test.c:1105: TINFO: Formatting /dev/loop0 with ext4 opts='' extra opts='' mke2fs 1.46.2 (28-Feb-2021) tst_test.c:1119: TINFO: Mounting /dev/loop0 to /ltp-tmp/ltp-aTUvKrI1Ui/LTP_stakwdp<6>[ 7738.791447] EXT4-fs (loop0): mounted filesystem fe0ff94a-6c04-4158-9b0e-069ac82b6c8d r/w with ordered data mode. Quota mode: none. zv/mntpoint fstyp=ext4 flags=0 <4>[ 7738.805833] ext4 filesystem being mounted at /ltp-tmp/ltp-aTUvKrI1Ui/LTP_stakwdpzv/mntpoint supports timestamps until 2038-01-19 (0x7fffffff) statvfs01.c:32: TPASS: statvfs(TEST_PATH, &buf) passed statvfs01.c:44: TPASS: creat(valid_fname, 0444) returned fd 3 statvfs01.c:48: TFAIL: creat(toolong_fname, 0<6>[ 7738.837563] EXT4-fs (loop0): unmounting filesystem fe0ff94a-6c04-4158-9b0e-069ac82b6c8d. 444) expected ENAMETOOLONG: EIO (5) tst_test.c:1650: TINFO: === Testing on tmpfs === tst_test.c:1105: TINFO: Skipping mkfs for TMPFS filesystem tst_test.c:1086: TINFO: Limiting tmpfs size to 32MB tst_test.c:1119: TINFO: Mounting ltp-tmpfs to /ltp-tmp/ltp-aTUvKrI1Ui/LTP_stakwdpzv/mntpoint fstyp=tmpfs flags=0 statvfs01.c:32: TPASS: statvfs(TEST_PATH, &buf) passed statvfs01.c:44: TPASS: creat(valid_fname, 0444) returned fd 3 statvfs01.c:48: TFAIL: creat(toolong_fname, 0444) expected ENAMETOOLONG: EIO (5) Summary: passed 8 failed 4 inotify02.c:165: TPASS: get event: wd=1 mask=40000004 cookie=0 len=0 name=\"\" inotify02.c:181: TFAIL: get event: wd=1 mask=00000020 (expected 100) cookie=0 len=16 name=\"test_file1\" (expected \"test_file1\") 0 inotify02.c:181: TFAIL: get event: wd=1 mask=00000100 (expected 20) cookie=0 len=16 name=\"test_file1\" (expected \"test_file1\") 0 inotify02.c:165: TPASS: get event: wd=1 mask=00000008 cookie=0 len=16 name=\"test_file1\" inotify02.c:165: TPASS: get event: wd=1 mask=00000040 cookie=5537 len=16 name=\"test_file1\" inotify02.c:165: TPASS: get event: wd=1 mask=00000080 cookie=5537 len=16 name=\"test_file2\" inotify02.c:165: TPASS: get event: wd=1 mask=00000800 cookie=0 len=0 name=\"\" inotify02.c:165: TPASS: get event: wd=1 mask=00000200 cookie=0 len=16 name=\"test_file2\" inotify02.c:165: TPASS: get event: wd=1 mask=00000800 cookie=0 len=0 name=\"\"
