[LU-4810] Mount command unexpectedly sets block device parameter "max_sectors_kb"

• Type: Bug
• Resolution: Fixed
• Priority: Major
• Fix Version/s: Lustre 2.7.0, Lustre 2.5.4
• Affects Version/s: Lustre 2.5.0
• Environment: RHEL 6.4/ distro IB ; Kernel 2.6.32-358.23.2.el6.atlas.x86_64 ; lustre-2.5.0 head
• Severity: 3
• Assignee: Niu Yawei (Inactive)
• Reporter: Blake Caldwell

Description

We've killed our MDT more than once because we were caught off guard by this behavior of the mount command. The array with the MDT devices doesn't support larger than 2kB transfers. The mpt2sas driver sets max_hw_sectors_kb to 16383, and then this code sets max_sectors_kb to 16383 as well. We run into problems when we scan the inodes (reading directly from block device) as part of our purge process.

We would prefer that the command just emit a warning instead of making the change.

http://git.whamcloud.com/?p=fs/lustre-release.git;a=blob;f=lustre/utils/mount_utils_ldiskfs.c;h=dfb9e6cba750a2a5a20e2d28d7814612522ab3a4;hb=HEAD#l1039

        snprintf(real_path, sizeof(real_path), "%s/%s", path,
                 MAX_HW_SECTORS_KB_PATH);
        rc = read_file(real_path, buf, sizeof(buf));
        if (rc) {
                if (verbose)
                        fprintf(stderr, "warning: opening %s: %s\n",
                                real_path, strerror(errno));
                /* No MAX_HW_SECTORS_KB_PATH isn't necessary an
                 * error for some device. */
                rc = 0;
        }

        if (strlen(buf) - 1 > 0) {
                snprintf(real_path, sizeof(real_path), "%s/%s", path,
                         MAX_SECTORS_KB_PATH);
                rc = write_file(real_path, buf);
                if (rc) {
                        if (verbose)
                                fprintf(stderr, "warning: writing to %s: %s\n",
                                        real_path, strerror(errno));
                        /* No MAX_SECTORS_KB_PATH isn't necessary an
                         * error for some device. */
                        rc = 0;
                }
        }

Issue Links

• is related to: LU-5888 mount.lustre: set max_sectors_kb to 2147483647