2 Bacula® - The Network Backup Solution
4 Copyright (C) 2009-2011 Free Software Foundation Europe e.V.
6 The main author of Bacula is Kern Sibbald, with contributions from
7 many others, a complete list can be found in the file AUTHORS.
8 This program is Free Software; you can redistribute it and/or
9 modify it under the terms of version three of the GNU Affero General Public
10 License as published by the Free Software Foundation and included
13 This program is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 General Public License for more details.
18 You should have received a copy of the GNU Affero General Public License
19 along with this program; if not, write to the Free Software
20 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
23 Bacula® is a registered trademark of Kern Sibbald.
24 The licensor of Bacula is the Free Software Foundation Europe
25 (FSFE), Fiduciary Program, Sumatrastrasse 25, 8006 Zürich,
26 Switzerland, email:ftf@fsfeurope.org.
30 * This code implements a cache with the current mounted filesystems for which
31 * its uses the mostly in kernel mount information and export the different OS
32 * specific interfaces using a generic interface. We use a hashed cache which is
33 * accessed using a hash on the device id and we keep the previous cache hit as
34 * most of the time we get called quite a lot with most of the time the same
35 * device so keeping the previous cache hit we have a very optimized code path.
37 * This interface is implemented for the following OS-es:
47 * Currently we only use this code for Linux and OSF1 based fstype determination.
48 * For the other OS-es we can use the fstype present in stat structure on those OS-es.
50 * This code replaces the big switch we used before based on SUPER_MAGIC present in
51 * the statfs(2) structure but which need extra code for each new filesystem added to
52 * the OS and for Linux that tends to be often as it has quite some different filesystems.
53 * This new implementation should eliminate this as we use the Linux /proc/mounts in kernel
54 * data which automatically adds any new filesystem when added to the kernel.
58 * Marco van Wieringen, August 2009
62 #include "mntent_cache.h"
67 #include <sys/types.h>
70 #if defined(HAVE_GETMNTENT)
71 #if defined(HAVE_LINUX_OS) || defined(HAVE_HPUX_OS) || defined(HAVE_AIX_OS)
73 #elif defined(HAVE_SUN_OS)
74 #include <sys/mnttab.h>
75 #endif /* HAVE_GETMNTENT */
76 #elif defined(HAVE_GETMNTINFO)
77 #if defined(HAVE_OPENBSD_OS)
78 #include <sys/param.h>
79 #include <sys/mount.h>
80 #elif defined(HAVE_NETBSD_OS)
81 #include <sys/types.h>
82 #include <sys/statvfs.h>
84 #include <sys/param.h>
85 #include <sys/ucred.h>
86 #include <sys/mount.h>
88 #elif defined(HAVE_AIX_OS)
91 #elif defined(HAVE_OSF1_OS)
92 #include <sys/mount.h>
96 * Protected data by mutex lock.
98 static pthread_mutex_t mntent_cache_lock = PTHREAD_MUTEX_INITIALIZER;
99 static mntent_cache_entry_t *previous_cache_hit = NULL;
100 static htable *mntent_cache_entry_hashtable = NULL;
103 * Last time a rescan of the mountlist took place.
105 static time_t last_rescan = 0;
108 * Add a new entry to the cache.
109 * This function should be called with a write lock on the mntent_cache.
111 static inline void add_mntent_mapping(uint32_t dev,
113 const char *mountpoint,
118 mntent_cache_entry_t *mce;
121 * Calculate the length of all strings so we can allocate the buffer
122 * as one big chunk of memory using the hash_malloc method.
124 len = strlen(special) + 1;
125 len += strlen(mountpoint) + 1;
126 len += strlen(fstype) + 1;
128 len += strlen(mntopts) + 1;
132 * We allocate all members of the hash entry in the same memory chunk.
134 mce = (mntent_cache_entry_t *)mntent_cache_entry_hashtable->hash_malloc(sizeof(mntent_cache_entry_t) + len);
137 mce->special = (char *)mce + sizeof(mntent_cache_entry_t);
138 strcpy(mce->special, special);
140 mce->mountpoint = mce->special + strlen(mce->special) + 1;
141 strcpy(mce->mountpoint, mountpoint);
143 mce->fstype = mce->mountpoint + strlen(mce->mountpoint) + 1;
144 strcpy(mce->fstype, fstype);
147 mce->mntopts = mce->fstype + strlen(mce->fstype) + 1;
148 strcpy(mce->mntopts, mntopts);
153 mntent_cache_entry_hashtable->insert(mce->dev, mce);
157 * OS specific function to load the different mntents into the cache.
158 * This function should be called with a write lock on the mntent_cache.
160 static void refresh_mount_cache(void)
162 #if defined(HAVE_GETMNTENT)
165 #if defined(HAVE_LINUX_OS) || defined(HAVE_HPUX_OS) || defined(HAVE_IRIX_OS) || defined(HAVE_AIX_OS)
168 #if defined(HAVE_LINUX_OS)
169 if ((fp = setmntent("/proc/mounts", "r")) == (FILE *)NULL) {
170 if ((fp = setmntent(_PATH_MOUNTED, "r")) == (FILE *)NULL) {
174 #elif defined(HAVE_HPUX_OS)
175 if ((fp = fopen(MNT_MNTTAB, "r")) == (FILE *)NULL) {
178 #elif defined(HAVE_IRIX_OS)
179 if ((fp = setmntent(MOUNTED, "r")) == (FILE *)NULL) {
182 #elif defined(HAVE_AIX_OS)
183 if ((fp = setmntent(MNTTAB, "r")) == (FILE *)NULL) {
188 while ((mnt = getmntent(fp)) != (struct mntent *)NULL) {
189 if (stat(mnt->mnt_dir, &st) < 0) {
193 add_mntent_mapping(st.st_dev, mnt->mnt_fsname, mnt->mnt_dir, mnt->mnt_type, mnt->mnt_opts);
197 #elif defined(HAVE_SUN_OS)
200 if ((fp = fopen(MNTTAB, "r")) == (FILE *)NULL)
203 while (getmntent(fp, &mnt) == 0) {
204 if (stat(mnt.mnt_mountp, &st) < 0) {
208 add_mntent_mapping(st.st_dev, mnt.mnt_special, mnt.mnt_mountp, mnt.mnt_fstype, mnt.mnt_mntopts);
212 #endif /* HAVE_SUN_OS */
213 #elif defined(HAVE_GETMNTINFO)
216 #if defined(HAVE_NETBSD_OS)
217 struct statvfs *mntinfo;
219 struct statfs *mntinfo;
221 #if defined(ST_NOWAIT)
222 int flags = ST_NOWAIT;
223 #elif defined(MNT_NOWAIT)
224 int flags = MNT_NOWAIT;
229 if ((cnt = getmntinfo(&mntinfo, flags)) > 0) {
231 if (stat(mntinfo->f_mntonname, &st) == 0) {
232 add_mntent_mapping(st.st_dev,
233 mntinfo->f_mntfromname,
234 mntinfo->f_mntonname,
235 mntinfo->f_fstypename,
242 #elif defined(HAVE_AIX_OS)
244 char *entries, *current;
250 if (mntctl(MCTL_QUERY, sizeof(bufsize), (struct vmount *)&bufsize) != 0) {
254 entries = malloc(bufsize);
255 if ((n_entries = mntctl(MCTL_QUERY, bufsize, (struct vmount *) entries)) < 0) {
262 while (cnt < n_entries) {
263 vmp = (struct vmount *)current;
265 if (stat(current + vmp->vmt_data[VMT_STUB].vmt_off, &st) < 0) {
269 ve = getvfsbytype(vmp->vmt_gfstype);
270 if (ve && ve->vfsent_name) {
271 add_mntent_mapping(st.st_dev,
272 current + vmp->vmt_data[VMT_OBJECT].vmt_off,
273 current + vmp->vmt_data[VMT_STUB].vmt_off,
275 current + vmp->vmt_data[VMT_ARGS].vmt_off);
277 current = current + vmp->vmt_length;
281 #elif defined(HAVE_OSF1_OS)
282 struct statfs *entries, *current;
287 if ((n_entries = getfsstat((struct statfs *)0, 0L, MNT_NOWAIT)) < 0) {
291 size = (n_entries + 1) * sizeof(struct statfs);
292 entries = malloc(size);
294 if ((n_entries = getfsstat(entries, size, MNT_NOWAIT)) < 0) {
301 while (cnt < n_entries) {
302 if (stat(current->f_mntonname, &st) < 0) {
305 add_mntent_mapping(st.st_dev,
306 current->f_mntfromname,
307 current->f_mntonname,
308 current->f_fstypename,
318 * Clear the cache (either by flushing it or by initializing it.)
319 * This function should be called with a write lock on the mntent_cache.
321 static void clear_mount_cache()
323 mntent_cache_entry_t *mce = NULL;
325 if (!mntent_cache_entry_hashtable) {
327 * Initialize the hash table.
329 mntent_cache_entry_hashtable = (htable *)malloc(sizeof(htable));
330 mntent_cache_entry_hashtable->init(mce, &mce->link,
331 NR_MNTENT_CACHE_ENTRIES,
332 NR_MNTENT_HTABLE_PAGES);
335 * Clear the previous_cache_hit.
337 previous_cache_hit = NULL;
340 * Destroy the current content and (re)initialize the hashtable.
342 mntent_cache_entry_hashtable->destroy();
343 mntent_cache_entry_hashtable->init(mce, &mce->link,
344 NR_MNTENT_CACHE_ENTRIES,
345 NR_MNTENT_HTABLE_PAGES);
350 * Initialize the cache for use.
351 * This function should be called with a write lock on the mntent_cache.
353 static void initialize_mntent_cache(void)
356 * Make sure the cache is empty (either by flushing it or by initializing it.)
363 refresh_mount_cache();
367 * Flush the current content from the cache.
369 void flush_mntent_cache(void)
374 P(mntent_cache_lock);
376 if (mntent_cache_entry_hashtable) {
377 previous_cache_hit = NULL;
378 mntent_cache_entry_hashtable->destroy();
379 mntent_cache_entry_hashtable = NULL;
382 V(mntent_cache_lock);
386 * Find a mapping in the cache.
388 mntent_cache_entry_t *find_mntent_mapping(uint32_t dev)
390 mntent_cache_entry_t *mce = NULL;
396 P(mntent_cache_lock);
399 * Shortcut when we get a request for the same device again.
401 if (previous_cache_hit && previous_cache_hit->dev == dev) {
402 mce = previous_cache_hit;
407 * Initialize the cache if that was not done before.
409 if (!mntent_cache_entry_hashtable) {
410 initialize_mntent_cache();
411 last_rescan = time(NULL);
414 * We rescan the mountlist when called when more then
415 * MNTENT_RESCAN_INTERVAL seconds have past since the
416 * last rescan. This way we never work with data older
417 * then MNTENT_RESCAN_INTERVAL seconds.
420 if ((now - last_rescan) > MNTENT_RESCAN_INTERVAL) {
421 initialize_mntent_cache();
425 mce = (mntent_cache_entry_t *)mntent_cache_entry_hashtable->lookup(dev);
428 * If we fail to lookup the mountpoint its probably a mountpoint added
429 * after we did our initial scan. Lets rescan the mountlist and try
433 initialize_mntent_cache();
434 mce = (mntent_cache_entry_t *)mntent_cache_entry_hashtable->lookup(dev);
438 * Store the last successfull lookup as the previous_cache_hit.
441 previous_cache_hit = mce;
445 V(mntent_cache_lock);