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<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">Hi, Gluster Experts,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">In glusterfs version 3.12.3, There seems a “fstat” issue for ctime after we use fsync,
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">We have a demo execute binary which write some data and then do fsync for this file, it named as “tt”,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">Then run tar command right after “tt” command, it will always error with “tar: /mnt/test/file1.txt: file changed as we read it”<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">The command output is list as the below, the source code and volume info configuration attached FYI,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">This issue will be 100% reproducible! (/mnt/test is mountpoint of glusterfs volume “test” , which the volume info is attached in mail)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">------------------------------------------------------------------<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">./tt;tar -czvf /tmp/abc.gz /mnt/test/file1.txt<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">mtime:1531247107.272000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">ctime:1531247107.272000000<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">tar: Removing leading `/' from member names<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">/mnt/test/file1.txt<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">tar: /mnt/test/file1.txt: file changed as we read it<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">----------------------------------------------------------------------<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">After my investigation, the xattrop for changelog is later than the fsync response , this is mean:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">In function “afr_fsync_cbk” will call afr_delayed_changelog_wake_resume (this, local->fd, stub);<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">In our case, it always a pending changelog , so glusterfs save the metadata information to stub, and handle pending changelog first,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">But the changelog will also change the ctime, from the packet captured by tcpdump, the response packet of xattrop will not include the metadata information, and the wake_resume
also not handle this metadata changed case.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">So in this case, the metadata in mdc_cache is not right, and when cache is valid, the application will get WRONG metadata!<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">For verify my guess, if I change the configuration for this volume<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:36.75pt"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">“gluster v set test md-cache-timeout 0” or<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:36.75pt"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">“gluster v set export stat-prefetch off”<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">This issue will be GONE!<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">And I restore the configuration to default, which mean stat-prefetch is on and md-cache-timeout is 1 second,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">I try invalidate the md-cache in source code as the below in function mdc_fync_cbk on md-cache.c<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">The issue also will be GONE!<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">So GLusterFS Experts,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">Could you please verify this issue, and share your comments on my investigation?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">And your finally solutions is highly appreciated!<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">------------------------------------changes in function “mdc_fsync_cbk”<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">int<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">mdc_fsync_cbk (call_frame_t *frame, void *cookie, xlator_t *this,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"> int32_t op_ret, int32_t op_errno,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"> struct iatt *prebuf, struct iatt *postbuf, dict_t *xdata)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">{<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"> mdc_local_t *local = NULL;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"> local = frame->local;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"> if (op_ret != 0)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"> goto out;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"> if (!local)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"> goto out;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"> mdc_inode_iatt_set_validate(this, local->fd->inode, prebuf, postbuf,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"> _gf_true);<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">/* new added for ctime issue*/<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"> mdc_inode_iatt_invalidate(this, local->fd->inode);
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">/* new added end*/<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">out:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"> MDC_STACK_UNWIND (fsync, frame, op_ret, op_errno, prebuf, postbuf,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"> xdata);<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian"> return 0;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">}<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">---------------------------------------------------------------------------------<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">Best Regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt;font-family:DengXian">George<o:p></o:p></span></p>
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