diff options
Diffstat (limited to 'conf/umount/umount_linux.c')
| -rw-r--r-- | conf/umount/umount_linux.c | 264 |
1 files changed, 264 insertions, 0 deletions
diff --git a/conf/umount/umount_linux.c b/conf/umount/umount_linux.c new file mode 100644 index 000000000000..873ecf23f662 --- /dev/null +++ b/conf/umount/umount_linux.c @@ -0,0 +1,264 @@ +/* + * 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) */ |