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Wed, 24 Jun 2026 04:18:41 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id Xoj+GqFaO2pqOgAAD6G6ig (envelope-from ); Wed, 24 Jun 2026 04:18:41 +0000 Date: Wed, 24 Jun 2026 01:18:39 -0300 From: Enzo Matsumiya To: Chunjie Zhu Cc: smfrench@gmail.com, linux-cifs@vger.kernel.org, linux-kernel@vger.kernel.org, lsahlber@redhat.com, pc@manguebit.com, samba-technical@lists.samba.org, sfrench@samba.org, sprasad@microsoft.com, tom@talpey.com Subject: Re: Subject: Re: [PATCH] fix smb client defer close causes file corruption Message-ID: References: <20260624034414.5087-1-chunjie.zhu@citrix.com> Precedence: bulk X-Mailing-List: linux-cifs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20260624034414.5087-1-chunjie.zhu@citrix.com> X-Spam-Flag: NO X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; FUZZY_RATELIMITED(0.00)[rspamd.com]; RCVD_VIA_SMTP_AUTH(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; ARC_NA(0.00)[]; RCVD_TLS_ALL(0.00)[]; MIME_TRACE(0.00)[0:+]; MISSING_XM_UA(0.00)[]; RCPT_COUNT_SEVEN(0.00)[10]; MID_RHS_MATCH_FROM(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[gmail.com,vger.kernel.org,redhat.com,manguebit.com,lists.samba.org,samba.org,microsoft.com,talpey.com]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,suse.de:mid] X-Spam-Level: X-Spam-Score: -4.30 On 06/24, Chunjie Zhu wrote: >>From my experience, these common workloads tend to occur within a single >process. Therefore, it might be worth optimizing cifs_get_readable_path >by extending its matching logic: instead of matching only the file path, >we could also check the process PID. The old handler would then be reused >only when both the file path and the PID match. > >Do you think this approach is viable? I don't think this is a good idea; PIDs change and are naturally made to be reused as well, so storing PID for a 'later' (no matter how later) check is 100% unreliable. As for the original bug report, do you happen to have a simple reproducer? I created one on top of your instructions and I'm definitely getting a lease break on rename, which IIUC is the alleged root cause. This was with closetimeo=30 on a Windows Server 2022 share. Also, I'm failing to understand how cache= has any impact on this -- I get the same successful results with none,loose,strict. Cheers, Enzo >> Other narrower client fixes for this presumably could be done, e.g. >> forcing close on the deferred close when rename a hardlink. >> >> On Mon, Jun 22, 2026 at 4:40=E2=80=AFAM Chunjie Zhu > > wrote: >> > >> > Test environment >> > >> > 4 hosts as smb client, 1 host as smb server >> > smb client hosts, kernel 6.6.138 >> > mount options, >> > //10.70.48.15/xxx /run/xxx cifs rw,relatime,vers=3D3.0, >> > cache=3Dloose,username=3Dxxx,domain=3Dxxx,uid=3D0,noforceuid, >> > gid=3D0,noforcegid,addr=3D10.70.48.15,file_mode=3D0755, >> > dir_mode=3D0755,soft,nounix,serverino,mapposix,reparse=3Dnfs, >> > rsize=3D1048576,wsize=3D1048576,bsize=3D1048576,echo_interval=3D60, >> > actimeo=3D0,closetimeo=3D1 >> > >> > Work around >> > >> > mount with cache=3Dnone or closetimeo=3D0 >> > >> > The Race Condition Flow >> > >> > Step 1: Host-01 closes file >> > >> > Host-01: >> > file close (eeefe8d0.vhd) >> > -> CIFS defers SMB2 CLOSE >> > -> Handle H1 stored in deferred_closes list >> > -> Lease L1 (RWH or RH) still active on server >> > -> Entry: { path=3D=E2=80=9Ceeefe8d0.vhd=E2=80=9D, handle=3DH1, inode= >> =3DI1 } >> > >> > Step 2: Host-02 does hardlink and rename >> > >> > Host-02: >> > hardlink(eeefe8d0.vhd, 0f11b74e.vhd) >> > -> SMB2: Creates new name for same inode >> > -> Server: inode I1 now has 2 names (link count =3D 2) >> > -> Host-01 lease L1: NO BREAK (same inode, just added name) >> > >> > crate(eeefe8d0.vhd.new) >> > -> Entry { path=3D"eeefe8d0.vhd.new", handle=3DH2, inode=3DI2 } >> > >> > rename(eeefe8d0.vhd.new, eeefe8d0.vhd) >> > -> SMB2: Replaces =E2=80=9Ceeefe8d0.vhd=E2=80=9D name =E2=86=92 points= >> to new inode I2 >> > -> Server: old inode I1 now only accessible as =E2=80=9C0f11b74e.vhd= >> =E2=80=9D >> > -> Server SHOULD send: Lease Break notification to H1 =E2=86=90 KEY! >> > >> > Step 3: Lease break delivery is not reliable >> > >> > strict locking off, level2 oplock >> > >> > Host-01: >> > -> Lease break not received or processed >> > -> H1 is in deferred_closes list (not "active") >> > >> > Result: Stale entry remains: >> > { path=3D=E2=80=9Ceeefe8d0.vhd=E2=80=9D, handle=3DH1, inode=3DI1_OL= >> D } >> > >> > Host-02: >> > -> Open 0f11b74e.vhd in readonly >> > >> > Result: >> > { path=3D"0f11b74e.vhd", inode=3DI1_NEW } >> > >> > Step 4: Host-01 reopens file >> > >> > Host-01: >> > file open (eeefe8d0.vhd) >> > -> Kernel checks deferred_closes for =E2=80=9Ceeefe8d0.vhd=E2=80=9D >> > -> Found H1! (matched by pathname string) >> > -> REUSES H1 without checking >> > -> close or reconnect, flush buffered writes >> > slient corruption? >> > >> > Signed-off-by: Chunjie Zhu >> > --- >> > fs/smb/client/fs_context.c | 8 ++++---- >> > 1 file changed, 4 insertions(+), 4 deletions(-) >> > >> > diff --git a/fs/smb/client/fs_context.c b/fs/smb/client/fs_context.c >> > index 0812af001417..4ed33de0a00d 100644 >> > --- a/fs/smb/client/fs_context.c >> > +++ b/fs/smb/client/fs_context.c >> > @@ -1300,11 +1300,11 @@ static int smb3_fs_context_parse_param(struct fs_= >> context *fc, >> > ctx->acdirmax =3D ctx->acregmax =3D HZ * result.uint_32; >> > break; >> > case Opt_closetimeo: >> > - if (result.uint_32 > SMB3_MAX_DCLOSETIMEO / HZ) { >> > - cifs_errorf(fc, "closetimeo too large\n"); >> > + if (result.uint_32 !=3D 0) { >> > + cifs_errorf(fc, "closetimeo must be 0, deferred c= >> lose is disabled\n"); >> > goto cifs_parse_mount_err; >> > } >> > - ctx->closetimeo =3D HZ * result.uint_32; >> > + ctx->closetimeo =3D 0; >> > break; >> > case Opt_echo_interval: >> > if (result.uint_32 < SMB_ECHO_INTERVAL_MIN || >> > @@ -1795,7 +1795,7 @@ int smb3_init_fs_context(struct fs_context *fc) >> > >> > ctx->acregmax =3D CIFS_DEF_ACTIMEO; >> > ctx->acdirmax =3D CIFS_DEF_ACTIMEO; >> > - ctx->closetimeo =3D SMB3_DEF_DCLOSETIMEO; >> > + ctx->closetimeo =3D 0; >> > ctx->max_cached_dirs =3D MAX_CACHED_FIDS; >> > /* Most clients set timeout to 0, allows server to use its defaul= >> t */ >> > ctx->handle_timeout =3D 0; /* See MS-SMB2 spec section 2.2.14.2.1= >> 2 */ >> > -- >> > 2.52.0 >> > >> > >> >> >> --=20 >> Thanks, >> >> Steve >> >