[LU-9936] ldiskfs_write_ldd() calls fsync(filep->_fileno) but doesn't fflush() flip first

• Status: Open
• Project: Lustre
• Type: Bug
• Priority: Minor
• Reporter: John Hammond
• Assignee: WC Triage
• Resolution: Unresolved
• Labels: easy, mount
• Severity: 3

Description

In ldiskfs_write_ldd():

 270         num = fwrite(&mop->mo_ldd, sizeof(mop->mo_ldd), 1, filep);
 271         if (num < 1 && ferror(filep)) {
 272                 fprintf(stderr, "%s: Unable to write to file (%s): %s\n",
 273                         progname, filepnm, strerror(errno));
 274                 fclose(filep);
 275                 goto out_umnt;
 276         }
 277         fsync(filep->_fileno);
 278         fclose(filep);
 

Calling fsync() without first calling fflush() is ineffective since there will likely still be unwritten data in the userspace buffer.

Also we should use fileno(filp) instead of accessing filp->_fileno.

We should check the returns of fflush(), fsync(), and fclose() for failure. Since an error is more likely to be reported there than from fwrite().

Comments

[John Hammond]

Andreas has pointed out that there is no reason to use stdio here.

[Andreas Dilger]

There doesn't appear to be a good reason for using buffered stream IO here. Instead, this should use Unix IO (open(), write(), fsync(), and close()).