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-rw-r--r--conf/umount/umount_linux.c264
1 files changed, 264 insertions, 0 deletions
diff --git a/conf/umount/umount_linux.c b/conf/umount/umount_linux.c
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+/*
+ * Copyright (c) 1997-2014 Erez Zadok
+ * Copyright (c) 1990 Jan-Simon Pendry
+ * Copyright (c) 1990 Imperial College of Science, Technology & Medicine
+ * Copyright (c) 1990 The Regents of the University of California.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Jan-Simon Pendry at Imperial College, London.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *
+ * File: am-utils/conf/umount/umount_linux.c
+ *
+ */
+
+/*
+ * Linux method of unmounting filesystems: if umount(2) failed with EIO or
+ * ESTALE, try umount2(2) with MNT_FORCE+MNT_DETACH.
+ */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif /* HAVE_CONFIG_H */
+#include <am_defs.h>
+#include <amu.h>
+
+
+int
+umount_fs(char *mntdir, const char *mnttabname, u_int unmount_flags)
+{
+ mntlist *mlist, *mp, *mp_save = NULL;
+ int error = 0;
+#ifdef HAVE_LOOP_DEVICE
+ char *opt, *xopts = NULL;
+ char loopstr[] = "loop=";
+ char *loopdev;
+#endif /* HAVE_LOOP_DEVICE */
+ unsigned int retries = 8;
+
+ mp = mlist = read_mtab(mntdir, mnttabname);
+
+ /*
+ * Search the mount table looking for
+ * the correct (ie last) matching entry
+ */
+ while (mp) {
+ if (STREQ(mp->mnt->mnt_dir, mntdir))
+ mp_save = mp;
+ mp = mp->mnext;
+ }
+
+ if (!mp_save) {
+ plog(XLOG_ERROR, "Couldn't find how to unmount %s", mntdir);
+ /* Assume it is already unmounted */
+ error = 0;
+ goto out;
+ }
+
+ plog(XLOG_ERROR, "Trying unmount %s, umount_flags 0x%x", mp_save->mnt->mnt_dir, unmount_flags);
+ dlog("Trying unmount(%s)", mp_save->mnt->mnt_dir);
+
+#ifdef MOUNT_TABLE_ON_FILE
+ /*
+ * This unmount may hang leaving this process with an exclusive lock on
+ * /etc/mtab. Therefore it is necessary to unlock mtab, do the unmount,
+ * then lock mtab (again) and reread it and finally update it.
+ */
+ unlock_mntlist();
+#endif /* MOUNT_TABLE_ON_FILE */
+
+again:
+#if defined(HAVE_UMOUNT2) && defined(MNT2_GEN_OPT_DETACH)
+ /*
+ * If user asked to try forced unmounts, then do a quick check to see if
+ * the mount point is hung badly. If so, then try to detach it by
+ * force; if the latter works, we're done.
+ */
+ if (unmount_flags & AMU_UMOUNT_DETACH) {
+ /*
+ * Note: we pass both DETACH and FORCE flags, because umount2_fs below
+ * (on Linux), should try FORCE before DETACH (the latter always
+ * succeeds).
+ */
+ error = umount2_fs(mp_save->mnt->mnt_dir,
+ unmount_flags & (AMU_UMOUNT_DETACH|AMU_UMOUNT_FORCE));
+ } else
+#endif /* defined(HAVE_UMOUNT2) && defined(MNT2_GEN_OPT_DETACH) */
+ error = UNMOUNT_TRAP(mp_save->mnt);
+
+ /* Linux kernel can be sluggish for some reason */
+ if (error == EBUSY && retries--) {
+ struct timespec tm = {0, 200000000};
+ nanosleep(&tm, NULL);
+ goto again;
+ }
+
+ if (error < 0) {
+ plog(XLOG_WARNING, "unmount(%s) failed: %m", mp_save->mnt->mnt_dir);
+ switch ((error = errno)) {
+ case EINVAL:
+ case ENOTBLK:
+ plog(XLOG_WARNING, "unmount: %s is not mounted", mp_save->mnt->mnt_dir);
+ error = 0; /* Not really an error */
+ break;
+
+ case ENOENT:
+ /*
+ * This could happen if the kernel insists on following symlinks
+ * when we try to unmount a direct mountpoint. We need to propagate
+ * the error up so that the top layers know it failed and don't
+ * try to rmdir() the mountpoint or other silly things.
+ */
+ plog(XLOG_ERROR, "mount point %s: %m", mp_save->mnt->mnt_dir);
+ break;
+
+#if defined(HAVE_UMOUNT2) && defined(MNT2_GEN_OPT_FORCE)
+ case EBUSY:
+ /*
+ * Caller determines if forced unmounts should be used now (for
+ * EBUSY). If caller asked to force an unmount, *and* the above
+ * "trivial" unmount attempt failed with EBUSY, then try to force
+ * the unmount.
+ */
+ if (unmount_flags & AMU_UMOUNT_FORCE) {
+ error = umount2_fs(mp_save->mnt->mnt_dir,
+ unmount_flags & AMU_UMOUNT_FORCE);
+ if (error < 0) {
+ plog(XLOG_WARNING, "%s: unmount/force: %m",
+ mp_save->mnt->mnt_dir);
+ error = errno;
+ }
+ }
+ break;
+#endif /* defined(HAVE_UMOUNT2) && defined(MNT2_GEN_OPT_FORCE) */
+
+ default:
+ dlog("%s: unmount: %m", mp_save->mnt->mnt_dir);
+ break;
+ }
+ } else {
+ dlog("unmount(%s) succeeded", mp_save->mnt->mnt_dir);
+ }
+ dlog("Finished unmount(%s)", mp_save->mnt->mnt_dir);
+
+ /*
+ * If we are successful or there was an ENOENT, remove
+ * the mount entry from the mtab file.
+ */
+ if (error && error != ENOENT)
+ goto out;
+
+#ifdef HAVE_LOOP_DEVICE
+ /* look for loop=/dev/loopX in mnt_opts */
+ xopts = xstrdup(mp_save->mnt->mnt_opts); /* b/c strtok is destructive */
+ for (opt = strtok(xopts, ","); opt; opt = strtok(NULL, ","))
+ if (NSTREQ(opt, loopstr, sizeof(loopstr) - 1)) {
+ loopdev = opt + sizeof(loopstr) - 1;
+ if (delete_loop_device(loopdev) < 0)
+ plog(XLOG_WARNING, "unmount() failed to release loop device %s: %m", loopdev);
+ else
+ plog(XLOG_INFO, "unmount() released loop device %s OK", loopdev);
+ break;
+ }
+ if (xopts)
+ XFREE(xopts);
+#endif /* HAVE_LOOP_DEVICE */
+
+#ifdef MOUNT_TABLE_ON_FILE
+ free_mntlist(mlist);
+ mp = mlist = read_mtab(mntdir, mnttabname);
+
+ /*
+ * Search the mount table looking for
+ * the correct (ie last) matching entry
+ */
+ mp_save = NULL;
+ while (mp) {
+ if (STREQ(mp->mnt->mnt_dir, mntdir))
+ mp_save = mp;
+ mp = mp->mnext;
+ }
+
+ if (mp_save) {
+ mnt_free(mp_save->mnt);
+ mp_save->mnt = NULL;
+ rewrite_mtab(mlist, mnttabname);
+ }
+#endif /* MOUNT_TABLE_ON_FILE */
+
+ out:
+ free_mntlist(mlist);
+
+ return error;
+}
+
+
+#if defined(HAVE_UMOUNT2) && (defined(MNT2_GEN_OPT_FORCE) || defined(MNT2_GEN_OPT_DETACH))
+/*
+ * Force unmount, no questions asked, without touching mnttab file. Try
+ * detach first because it is safer: will remove the hung mnt point without
+ * affecting hung applications. "Force" is more risky: it will cause the
+ * kernel to return EIO to applications stuck on a stat(2) of Amd.
+ */
+int
+umount2_fs(const char *mntdir, u_int unmount_flags)
+{
+ int error = 0;
+
+#ifdef MNT2_GEN_OPT_DETACH
+ if (unmount_flags & AMU_UMOUNT_DETACH) {
+ error = umount2(mntdir, MNT2_GEN_OPT_DETACH);
+ if (error < 0 && (errno == EINVAL || errno == ENOENT))
+ error = 0; /* ignore EINVAL/ENOENT */
+ if (error < 0) { /* don't try FORCE if detach succeeded */
+ plog(XLOG_WARNING, "%s: unmount/detach: %m", mntdir);
+ /* fall through to try "force" (if flag specified) */
+ } else {
+ dlog("%s: unmount/detach: OK", mntdir);
+ return error;
+ }
+ }
+#endif /* MNT2_GEN_OPT_DETACH */
+
+#ifdef MNT2_GEN_OPT_FORCE
+ if (unmount_flags & AMU_UMOUNT_FORCE) {
+ plog(XLOG_INFO, "umount2_fs: trying unmount/forced on %s", mntdir);
+ error = umount2(mntdir, MNT2_GEN_OPT_FORCE);
+ if (error < 0 && (errno == EINVAL || errno == ENOENT))
+ error = 0; /* ignore EINVAL/ENOENT */
+ if (error < 0)
+ plog(XLOG_WARNING, "%s: unmount/force: %m", mntdir);
+ else
+ dlog("%s: unmount/force: OK", mntdir);
+ /* fall through to return whatever error we got (if any) */
+ }
+#endif /* MNT2_GEN_OPT_FORCE */
+
+ return error;
+}
+#endif /* HAVE_UMOUNT2 && (MNT2_GEN_OPT_FORCE || MNT2_GEN_OPT_DETACH) */