2 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License as
7 * published by the Free Software Foundation.
9 * This program is distributed in the hope that it would be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
20 #include "xfs_shared.h"
21 #include "xfs_format.h"
22 #include "xfs_log_format.h"
23 #include "xfs_trans_resv.h"
26 #include "xfs_mount.h"
27 #include "xfs_da_format.h"
28 #include "xfs_da_btree.h"
29 #include "xfs_inode.h"
31 #include "xfs_ialloc.h"
32 #include "xfs_alloc.h"
33 #include "xfs_rtalloc.h"
35 #include "xfs_trans.h"
36 #include "xfs_trans_priv.h"
38 #include "xfs_error.h"
39 #include "xfs_quota.h"
40 #include "xfs_fsops.h"
41 #include "xfs_trace.h"
42 #include "xfs_icache.h"
43 #include "xfs_sysfs.h"
47 STATIC void xfs_icsb_balance_counter(xfs_mount_t *, xfs_sb_field_t,
49 STATIC void xfs_icsb_balance_counter_locked(xfs_mount_t *, xfs_sb_field_t,
51 STATIC void xfs_icsb_disable_counter(xfs_mount_t *, xfs_sb_field_t);
54 #define xfs_icsb_balance_counter(mp, a, b) do { } while (0)
55 #define xfs_icsb_balance_counter_locked(mp, a, b) do { } while (0)
58 static DEFINE_MUTEX(xfs_uuid_table_mutex);
59 static int xfs_uuid_table_size;
60 static uuid_t *xfs_uuid_table;
63 * See if the UUID is unique among mounted XFS filesystems.
64 * Mount fails if UUID is nil or a FS with the same UUID is already mounted.
70 uuid_t *uuid = &mp->m_sb.sb_uuid;
73 if (mp->m_flags & XFS_MOUNT_NOUUID)
76 if (uuid_is_nil(uuid)) {
77 xfs_warn(mp, "Filesystem has nil UUID - can't mount");
81 mutex_lock(&xfs_uuid_table_mutex);
82 for (i = 0, hole = -1; i < xfs_uuid_table_size; i++) {
83 if (uuid_is_nil(&xfs_uuid_table[i])) {
87 if (uuid_equal(uuid, &xfs_uuid_table[i]))
92 xfs_uuid_table = kmem_realloc(xfs_uuid_table,
93 (xfs_uuid_table_size + 1) * sizeof(*xfs_uuid_table),
94 xfs_uuid_table_size * sizeof(*xfs_uuid_table),
96 hole = xfs_uuid_table_size++;
98 xfs_uuid_table[hole] = *uuid;
99 mutex_unlock(&xfs_uuid_table_mutex);
104 mutex_unlock(&xfs_uuid_table_mutex);
105 xfs_warn(mp, "Filesystem has duplicate UUID %pU - can't mount", uuid);
111 struct xfs_mount *mp)
113 uuid_t *uuid = &mp->m_sb.sb_uuid;
116 if (mp->m_flags & XFS_MOUNT_NOUUID)
119 mutex_lock(&xfs_uuid_table_mutex);
120 for (i = 0; i < xfs_uuid_table_size; i++) {
121 if (uuid_is_nil(&xfs_uuid_table[i]))
123 if (!uuid_equal(uuid, &xfs_uuid_table[i]))
125 memset(&xfs_uuid_table[i], 0, sizeof(uuid_t));
128 ASSERT(i < xfs_uuid_table_size);
129 mutex_unlock(&xfs_uuid_table_mutex);
135 struct rcu_head *head)
137 struct xfs_perag *pag = container_of(head, struct xfs_perag, rcu_head);
139 ASSERT(atomic_read(&pag->pag_ref) == 0);
144 * Free up the per-ag resources associated with the mount structure.
151 struct xfs_perag *pag;
153 for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
154 spin_lock(&mp->m_perag_lock);
155 pag = radix_tree_delete(&mp->m_perag_tree, agno);
156 spin_unlock(&mp->m_perag_lock);
158 ASSERT(atomic_read(&pag->pag_ref) == 0);
159 call_rcu(&pag->rcu_head, __xfs_free_perag);
164 * Check size of device based on the (data/realtime) block count.
165 * Note: this check is used by the growfs code as well as mount.
168 xfs_sb_validate_fsb_count(
172 ASSERT(PAGE_SHIFT >= sbp->sb_blocklog);
173 ASSERT(sbp->sb_blocklog >= BBSHIFT);
175 /* Limited by ULONG_MAX of page cache index */
176 if (nblocks >> (PAGE_CACHE_SHIFT - sbp->sb_blocklog) > ULONG_MAX)
182 xfs_initialize_perag(
184 xfs_agnumber_t agcount,
185 xfs_agnumber_t *maxagi)
187 xfs_agnumber_t index;
188 xfs_agnumber_t first_initialised = 0;
192 xfs_sb_t *sbp = &mp->m_sb;
196 * Walk the current per-ag tree so we don't try to initialise AGs
197 * that already exist (growfs case). Allocate and insert all the
198 * AGs we don't find ready for initialisation.
200 for (index = 0; index < agcount; index++) {
201 pag = xfs_perag_get(mp, index);
206 if (!first_initialised)
207 first_initialised = index;
209 pag = kmem_zalloc(sizeof(*pag), KM_MAYFAIL);
212 pag->pag_agno = index;
214 spin_lock_init(&pag->pag_ici_lock);
215 mutex_init(&pag->pag_ici_reclaim_lock);
216 INIT_RADIX_TREE(&pag->pag_ici_root, GFP_ATOMIC);
217 spin_lock_init(&pag->pag_buf_lock);
218 pag->pag_buf_tree = RB_ROOT;
220 if (radix_tree_preload(GFP_NOFS))
223 spin_lock(&mp->m_perag_lock);
224 if (radix_tree_insert(&mp->m_perag_tree, index, pag)) {
226 spin_unlock(&mp->m_perag_lock);
227 radix_tree_preload_end();
231 spin_unlock(&mp->m_perag_lock);
232 radix_tree_preload_end();
236 * If we mount with the inode64 option, or no inode overflows
237 * the legacy 32-bit address space clear the inode32 option.
239 agino = XFS_OFFBNO_TO_AGINO(mp, sbp->sb_agblocks - 1, 0);
240 ino = XFS_AGINO_TO_INO(mp, agcount - 1, agino);
242 if ((mp->m_flags & XFS_MOUNT_SMALL_INUMS) && ino > XFS_MAXINUMBER_32)
243 mp->m_flags |= XFS_MOUNT_32BITINODES;
245 mp->m_flags &= ~XFS_MOUNT_32BITINODES;
247 if (mp->m_flags & XFS_MOUNT_32BITINODES)
248 index = xfs_set_inode32(mp, agcount);
250 index = xfs_set_inode64(mp, agcount);
258 for (; index > first_initialised; index--) {
259 pag = radix_tree_delete(&mp->m_perag_tree, index);
268 * Does the initial read of the superblock.
272 struct xfs_mount *mp,
275 unsigned int sector_size;
277 struct xfs_sb *sbp = &mp->m_sb;
279 int loud = !(flags & XFS_MFSI_QUIET);
280 const struct xfs_buf_ops *buf_ops;
282 ASSERT(mp->m_sb_bp == NULL);
283 ASSERT(mp->m_ddev_targp != NULL);
286 * For the initial read, we must guess at the sector
287 * size based on the block device. It's enough to
288 * get the sb_sectsize out of the superblock and
289 * then reread with the proper length.
290 * We don't verify it yet, because it may not be complete.
292 sector_size = xfs_getsize_buftarg(mp->m_ddev_targp);
296 * Allocate a (locked) buffer to hold the superblock.
297 * This will be kept around at all times to optimize
298 * access to the superblock.
301 error = xfs_buf_read_uncached(mp->m_ddev_targp, XFS_SB_DADDR,
302 BTOBB(sector_size), 0, &bp, buf_ops);
305 xfs_warn(mp, "SB validate failed with error %d.", error);
306 /* bad CRC means corrupted metadata */
307 if (error == -EFSBADCRC)
308 error = -EFSCORRUPTED;
313 * Initialize the mount structure from the superblock.
315 xfs_sb_from_disk(sbp, XFS_BUF_TO_SBP(bp));
318 * If we haven't validated the superblock, do so now before we try
319 * to check the sector size and reread the superblock appropriately.
321 if (sbp->sb_magicnum != XFS_SB_MAGIC) {
323 xfs_warn(mp, "Invalid superblock magic number");
329 * We must be able to do sector-sized and sector-aligned IO.
331 if (sector_size > sbp->sb_sectsize) {
333 xfs_warn(mp, "device supports %u byte sectors (not %u)",
334 sector_size, sbp->sb_sectsize);
339 if (buf_ops == NULL) {
341 * Re-read the superblock so the buffer is correctly sized,
342 * and properly verified.
345 sector_size = sbp->sb_sectsize;
346 buf_ops = loud ? &xfs_sb_buf_ops : &xfs_sb_quiet_buf_ops;
350 /* Initialize per-cpu counters */
351 xfs_icsb_reinit_counters(mp);
353 /* no need to be quiet anymore, so reset the buf ops */
354 bp->b_ops = &xfs_sb_buf_ops;
366 * Update alignment values based on mount options and sb values
369 xfs_update_alignment(xfs_mount_t *mp)
371 xfs_sb_t *sbp = &(mp->m_sb);
375 * If stripe unit and stripe width are not multiples
376 * of the fs blocksize turn off alignment.
378 if ((BBTOB(mp->m_dalign) & mp->m_blockmask) ||
379 (BBTOB(mp->m_swidth) & mp->m_blockmask)) {
381 "alignment check failed: sunit/swidth vs. blocksize(%d)",
386 * Convert the stripe unit and width to FSBs.
388 mp->m_dalign = XFS_BB_TO_FSBT(mp, mp->m_dalign);
389 if (mp->m_dalign && (sbp->sb_agblocks % mp->m_dalign)) {
391 "alignment check failed: sunit/swidth vs. agsize(%d)",
394 } else if (mp->m_dalign) {
395 mp->m_swidth = XFS_BB_TO_FSBT(mp, mp->m_swidth);
398 "alignment check failed: sunit(%d) less than bsize(%d)",
399 mp->m_dalign, sbp->sb_blocksize);
405 * Update superblock with new values
408 if (xfs_sb_version_hasdalign(sbp)) {
409 if (sbp->sb_unit != mp->m_dalign) {
410 sbp->sb_unit = mp->m_dalign;
411 mp->m_update_sb = true;
413 if (sbp->sb_width != mp->m_swidth) {
414 sbp->sb_width = mp->m_swidth;
415 mp->m_update_sb = true;
419 "cannot change alignment: superblock does not support data alignment");
422 } else if ((mp->m_flags & XFS_MOUNT_NOALIGN) != XFS_MOUNT_NOALIGN &&
423 xfs_sb_version_hasdalign(&mp->m_sb)) {
424 mp->m_dalign = sbp->sb_unit;
425 mp->m_swidth = sbp->sb_width;
432 * Set the maximum inode count for this filesystem
435 xfs_set_maxicount(xfs_mount_t *mp)
437 xfs_sb_t *sbp = &(mp->m_sb);
440 if (sbp->sb_imax_pct) {
442 * Make sure the maximum inode count is a multiple
443 * of the units we allocate inodes in.
445 icount = sbp->sb_dblocks * sbp->sb_imax_pct;
447 do_div(icount, mp->m_ialloc_blks);
448 mp->m_maxicount = (icount * mp->m_ialloc_blks) <<
456 * Set the default minimum read and write sizes unless
457 * already specified in a mount option.
458 * We use smaller I/O sizes when the file system
459 * is being used for NFS service (wsync mount option).
462 xfs_set_rw_sizes(xfs_mount_t *mp)
464 xfs_sb_t *sbp = &(mp->m_sb);
465 int readio_log, writeio_log;
467 if (!(mp->m_flags & XFS_MOUNT_DFLT_IOSIZE)) {
468 if (mp->m_flags & XFS_MOUNT_WSYNC) {
469 readio_log = XFS_WSYNC_READIO_LOG;
470 writeio_log = XFS_WSYNC_WRITEIO_LOG;
472 readio_log = XFS_READIO_LOG_LARGE;
473 writeio_log = XFS_WRITEIO_LOG_LARGE;
476 readio_log = mp->m_readio_log;
477 writeio_log = mp->m_writeio_log;
480 if (sbp->sb_blocklog > readio_log) {
481 mp->m_readio_log = sbp->sb_blocklog;
483 mp->m_readio_log = readio_log;
485 mp->m_readio_blocks = 1 << (mp->m_readio_log - sbp->sb_blocklog);
486 if (sbp->sb_blocklog > writeio_log) {
487 mp->m_writeio_log = sbp->sb_blocklog;
489 mp->m_writeio_log = writeio_log;
491 mp->m_writeio_blocks = 1 << (mp->m_writeio_log - sbp->sb_blocklog);
495 * precalculate the low space thresholds for dynamic speculative preallocation.
498 xfs_set_low_space_thresholds(
499 struct xfs_mount *mp)
503 for (i = 0; i < XFS_LOWSP_MAX; i++) {
504 __uint64_t space = mp->m_sb.sb_dblocks;
507 mp->m_low_space[i] = space * (i + 1);
513 * Set whether we're using inode alignment.
516 xfs_set_inoalignment(xfs_mount_t *mp)
518 if (xfs_sb_version_hasalign(&mp->m_sb) &&
519 mp->m_sb.sb_inoalignmt >=
520 XFS_B_TO_FSBT(mp, mp->m_inode_cluster_size))
521 mp->m_inoalign_mask = mp->m_sb.sb_inoalignmt - 1;
523 mp->m_inoalign_mask = 0;
525 * If we are using stripe alignment, check whether
526 * the stripe unit is a multiple of the inode alignment
528 if (mp->m_dalign && mp->m_inoalign_mask &&
529 !(mp->m_dalign & mp->m_inoalign_mask))
530 mp->m_sinoalign = mp->m_dalign;
536 * Check that the data (and log if separate) is an ok size.
540 struct xfs_mount *mp)
546 d = (xfs_daddr_t)XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks);
547 if (XFS_BB_TO_FSB(mp, d) != mp->m_sb.sb_dblocks) {
548 xfs_warn(mp, "filesystem size mismatch detected");
551 error = xfs_buf_read_uncached(mp->m_ddev_targp,
552 d - XFS_FSS_TO_BB(mp, 1),
553 XFS_FSS_TO_BB(mp, 1), 0, &bp, NULL);
555 xfs_warn(mp, "last sector read failed");
560 if (mp->m_logdev_targp == mp->m_ddev_targp)
563 d = (xfs_daddr_t)XFS_FSB_TO_BB(mp, mp->m_sb.sb_logblocks);
564 if (XFS_BB_TO_FSB(mp, d) != mp->m_sb.sb_logblocks) {
565 xfs_warn(mp, "log size mismatch detected");
568 error = xfs_buf_read_uncached(mp->m_logdev_targp,
569 d - XFS_FSB_TO_BB(mp, 1),
570 XFS_FSB_TO_BB(mp, 1), 0, &bp, NULL);
572 xfs_warn(mp, "log device read failed");
580 * Clear the quotaflags in memory and in the superblock.
583 xfs_mount_reset_sbqflags(
584 struct xfs_mount *mp)
588 /* It is OK to look at sb_qflags in the mount path without m_sb_lock. */
589 if (mp->m_sb.sb_qflags == 0)
591 spin_lock(&mp->m_sb_lock);
592 mp->m_sb.sb_qflags = 0;
593 spin_unlock(&mp->m_sb_lock);
595 if (!xfs_fs_writable(mp, SB_FREEZE_WRITE))
598 return xfs_sync_sb(mp, false);
602 xfs_default_resblks(xfs_mount_t *mp)
607 * We default to 5% or 8192 fsbs of space reserved, whichever is
608 * smaller. This is intended to cover concurrent allocation
609 * transactions when we initially hit enospc. These each require a 4
610 * block reservation. Hence by default we cover roughly 2000 concurrent
611 * allocation reservations.
613 resblks = mp->m_sb.sb_dblocks;
615 resblks = min_t(__uint64_t, resblks, 8192);
620 * This function does the following on an initial mount of a file system:
621 * - reads the superblock from disk and init the mount struct
622 * - if we're a 32-bit kernel, do a size check on the superblock
623 * so we don't mount terabyte filesystems
624 * - init mount struct realtime fields
625 * - allocate inode hash table for fs
626 * - init directory manager
627 * - perform recovery and init the log manager
633 xfs_sb_t *sbp = &(mp->m_sb);
640 xfs_sb_mount_common(mp, sbp);
643 * Check for a mismatched features2 values. Older kernels read & wrote
644 * into the wrong sb offset for sb_features2 on some platforms due to
645 * xfs_sb_t not being 64bit size aligned when sb_features2 was added,
646 * which made older superblock reading/writing routines swap it as a
649 * For backwards compatibility, we make both slots equal.
651 * If we detect a mismatched field, we OR the set bits into the existing
652 * features2 field in case it has already been modified; we don't want
653 * to lose any features. We then update the bad location with the ORed
654 * value so that older kernels will see any features2 flags. The
655 * superblock writeback code ensures the new sb_features2 is copied to
656 * sb_bad_features2 before it is logged or written to disk.
658 if (xfs_sb_has_mismatched_features2(sbp)) {
659 xfs_warn(mp, "correcting sb_features alignment problem");
660 sbp->sb_features2 |= sbp->sb_bad_features2;
661 mp->m_update_sb = true;
664 * Re-check for ATTR2 in case it was found in bad_features2
667 if (xfs_sb_version_hasattr2(&mp->m_sb) &&
668 !(mp->m_flags & XFS_MOUNT_NOATTR2))
669 mp->m_flags |= XFS_MOUNT_ATTR2;
672 if (xfs_sb_version_hasattr2(&mp->m_sb) &&
673 (mp->m_flags & XFS_MOUNT_NOATTR2)) {
674 xfs_sb_version_removeattr2(&mp->m_sb);
675 mp->m_update_sb = true;
677 /* update sb_versionnum for the clearing of the morebits */
678 if (!sbp->sb_features2)
679 mp->m_update_sb = true;
682 /* always use v2 inodes by default now */
683 if (!(mp->m_sb.sb_versionnum & XFS_SB_VERSION_NLINKBIT)) {
684 mp->m_sb.sb_versionnum |= XFS_SB_VERSION_NLINKBIT;
685 mp->m_update_sb = true;
689 * Check if sb_agblocks is aligned at stripe boundary
690 * If sb_agblocks is NOT aligned turn off m_dalign since
691 * allocator alignment is within an ag, therefore ag has
692 * to be aligned at stripe boundary.
694 error = xfs_update_alignment(mp);
698 xfs_alloc_compute_maxlevels(mp);
699 xfs_bmap_compute_maxlevels(mp, XFS_DATA_FORK);
700 xfs_bmap_compute_maxlevels(mp, XFS_ATTR_FORK);
701 xfs_ialloc_compute_maxlevels(mp);
703 xfs_set_maxicount(mp);
705 error = xfs_sysfs_init(&mp->m_kobj, &xfs_mp_ktype, NULL, mp->m_fsname);
709 error = xfs_uuid_mount(mp);
711 goto out_remove_sysfs;
714 * Set the minimum read and write sizes
716 xfs_set_rw_sizes(mp);
718 /* set the low space thresholds for dynamic preallocation */
719 xfs_set_low_space_thresholds(mp);
722 * Set the inode cluster size.
723 * This may still be overridden by the file system
724 * block size if it is larger than the chosen cluster size.
726 * For v5 filesystems, scale the cluster size with the inode size to
727 * keep a constant ratio of inode per cluster buffer, but only if mkfs
728 * has set the inode alignment value appropriately for larger cluster
731 mp->m_inode_cluster_size = XFS_INODE_BIG_CLUSTER_SIZE;
732 if (xfs_sb_version_hascrc(&mp->m_sb)) {
733 int new_size = mp->m_inode_cluster_size;
735 new_size *= mp->m_sb.sb_inodesize / XFS_DINODE_MIN_SIZE;
736 if (mp->m_sb.sb_inoalignmt >= XFS_B_TO_FSBT(mp, new_size))
737 mp->m_inode_cluster_size = new_size;
741 * Set inode alignment fields
743 xfs_set_inoalignment(mp);
746 * Check that the data (and log if separate) is an ok size.
748 error = xfs_check_sizes(mp);
750 goto out_remove_uuid;
753 * Initialize realtime fields in the mount structure
755 error = xfs_rtmount_init(mp);
757 xfs_warn(mp, "RT mount failed");
758 goto out_remove_uuid;
762 * Copies the low order bits of the timestamp and the randomly
763 * set "sequence" number out of a UUID.
765 uuid_getnodeuniq(&sbp->sb_uuid, mp->m_fixedfsid);
767 mp->m_dmevmask = 0; /* not persistent; set after each mount */
769 error = xfs_da_mount(mp);
771 xfs_warn(mp, "Failed dir/attr init: %d", error);
772 goto out_remove_uuid;
776 * Initialize the precomputed transaction reservations values.
781 * Allocate and initialize the per-ag data.
783 spin_lock_init(&mp->m_perag_lock);
784 INIT_RADIX_TREE(&mp->m_perag_tree, GFP_ATOMIC);
785 error = xfs_initialize_perag(mp, sbp->sb_agcount, &mp->m_maxagi);
787 xfs_warn(mp, "Failed per-ag init: %d", error);
791 if (!sbp->sb_logblocks) {
792 xfs_warn(mp, "no log defined");
793 XFS_ERROR_REPORT("xfs_mountfs", XFS_ERRLEVEL_LOW, mp);
794 error = -EFSCORRUPTED;
799 * log's mount-time initialization. Perform 1st part recovery if needed
801 error = xfs_log_mount(mp, mp->m_logdev_targp,
802 XFS_FSB_TO_DADDR(mp, sbp->sb_logstart),
803 XFS_FSB_TO_BB(mp, sbp->sb_logblocks));
805 xfs_warn(mp, "log mount failed");
810 * Now the log is mounted, we know if it was an unclean shutdown or
811 * not. If it was, with the first phase of recovery has completed, we
812 * have consistent AG blocks on disk. We have not recovered EFIs yet,
813 * but they are recovered transactionally in the second recovery phase
816 * Hence we can safely re-initialise incore superblock counters from
817 * the per-ag data. These may not be correct if the filesystem was not
818 * cleanly unmounted, so we need to wait for recovery to finish before
821 * If the filesystem was cleanly unmounted, then we can trust the
822 * values in the superblock to be correct and we don't need to do
825 * If we are currently making the filesystem, the initialisation will
826 * fail as the perag data is in an undefined state.
828 if (xfs_sb_version_haslazysbcount(&mp->m_sb) &&
829 !XFS_LAST_UNMOUNT_WAS_CLEAN(mp) &&
830 !mp->m_sb.sb_inprogress) {
831 error = xfs_initialize_perag_data(mp, sbp->sb_agcount);
833 goto out_log_dealloc;
837 * Get and sanity-check the root inode.
838 * Save the pointer to it in the mount structure.
840 error = xfs_iget(mp, NULL, sbp->sb_rootino, 0, XFS_ILOCK_EXCL, &rip);
842 xfs_warn(mp, "failed to read root inode");
843 goto out_log_dealloc;
848 if (unlikely(!S_ISDIR(rip->i_d.di_mode))) {
849 xfs_warn(mp, "corrupted root inode %llu: not a directory",
850 (unsigned long long)rip->i_ino);
851 xfs_iunlock(rip, XFS_ILOCK_EXCL);
852 XFS_ERROR_REPORT("xfs_mountfs_int(2)", XFS_ERRLEVEL_LOW,
854 error = -EFSCORRUPTED;
857 mp->m_rootip = rip; /* save it */
859 xfs_iunlock(rip, XFS_ILOCK_EXCL);
862 * Initialize realtime inode pointers in the mount structure
864 error = xfs_rtmount_inodes(mp);
867 * Free up the root inode.
869 xfs_warn(mp, "failed to read RT inodes");
874 * If this is a read-only mount defer the superblock updates until
875 * the next remount into writeable mode. Otherwise we would never
876 * perform the update e.g. for the root filesystem.
878 if (mp->m_update_sb && !(mp->m_flags & XFS_MOUNT_RDONLY)) {
879 error = xfs_sync_sb(mp, false);
881 xfs_warn(mp, "failed to write sb changes");
887 * Initialise the XFS quota management subsystem for this mount
889 if (XFS_IS_QUOTA_RUNNING(mp)) {
890 error = xfs_qm_newmount(mp, "amount, "aflags);
894 ASSERT(!XFS_IS_QUOTA_ON(mp));
897 * If a file system had quotas running earlier, but decided to
898 * mount without -o uquota/pquota/gquota options, revoke the
899 * quotachecked license.
901 if (mp->m_sb.sb_qflags & XFS_ALL_QUOTA_ACCT) {
902 xfs_notice(mp, "resetting quota flags");
903 error = xfs_mount_reset_sbqflags(mp);
910 * Finish recovering the file system. This part needed to be
911 * delayed until after the root and real-time bitmap inodes
912 * were consistently read in.
914 error = xfs_log_mount_finish(mp);
916 xfs_warn(mp, "log mount finish failed");
921 * Complete the quota initialisation, post-log-replay component.
924 ASSERT(mp->m_qflags == 0);
925 mp->m_qflags = quotaflags;
927 xfs_qm_mount_quotas(mp);
931 * Now we are mounted, reserve a small amount of unused space for
932 * privileged transactions. This is needed so that transaction
933 * space required for critical operations can dip into this pool
934 * when at ENOSPC. This is needed for operations like create with
935 * attr, unwritten extent conversion at ENOSPC, etc. Data allocations
936 * are not allowed to use this reserved space.
938 * This may drive us straight to ENOSPC on mount, but that implies
939 * we were already there on the last unmount. Warn if this occurs.
941 if (!(mp->m_flags & XFS_MOUNT_RDONLY)) {
942 resblks = xfs_default_resblks(mp);
943 error = xfs_reserve_blocks(mp, &resblks, NULL);
946 "Unable to allocate reserve blocks. Continuing without reserve pool.");
952 xfs_rtunmount_inodes(mp);
958 if (mp->m_logdev_targp && mp->m_logdev_targp != mp->m_ddev_targp)
959 xfs_wait_buftarg(mp->m_logdev_targp);
960 xfs_wait_buftarg(mp->m_ddev_targp);
966 xfs_uuid_unmount(mp);
968 xfs_sysfs_del(&mp->m_kobj);
974 * This flushes out the inodes,dquots and the superblock, unmounts the
975 * log and makes sure that incore structures are freed.
979 struct xfs_mount *mp)
984 cancel_delayed_work_sync(&mp->m_eofblocks_work);
986 xfs_qm_unmount_quotas(mp);
987 xfs_rtunmount_inodes(mp);
991 * We can potentially deadlock here if we have an inode cluster
992 * that has been freed has its buffer still pinned in memory because
993 * the transaction is still sitting in a iclog. The stale inodes
994 * on that buffer will have their flush locks held until the
995 * transaction hits the disk and the callbacks run. the inode
996 * flush takes the flush lock unconditionally and with nothing to
997 * push out the iclog we will never get that unlocked. hence we
998 * need to force the log first.
1000 xfs_log_force(mp, XFS_LOG_SYNC);
1003 * Flush all pending changes from the AIL.
1005 xfs_ail_push_all_sync(mp->m_ail);
1008 * And reclaim all inodes. At this point there should be no dirty
1009 * inodes and none should be pinned or locked, but use synchronous
1010 * reclaim just to be sure. We can stop background inode reclaim
1011 * here as well if it is still running.
1013 cancel_delayed_work_sync(&mp->m_reclaim_work);
1014 xfs_reclaim_inodes(mp, SYNC_WAIT);
1019 * Unreserve any blocks we have so that when we unmount we don't account
1020 * the reserved free space as used. This is really only necessary for
1021 * lazy superblock counting because it trusts the incore superblock
1022 * counters to be absolutely correct on clean unmount.
1024 * We don't bother correcting this elsewhere for lazy superblock
1025 * counting because on mount of an unclean filesystem we reconstruct the
1026 * correct counter value and this is irrelevant.
1028 * For non-lazy counter filesystems, this doesn't matter at all because
1029 * we only every apply deltas to the superblock and hence the incore
1030 * value does not matter....
1033 error = xfs_reserve_blocks(mp, &resblks, NULL);
1035 xfs_warn(mp, "Unable to free reserved block pool. "
1036 "Freespace may not be correct on next mount.");
1038 error = xfs_log_sbcount(mp);
1040 xfs_warn(mp, "Unable to update superblock counters. "
1041 "Freespace may not be correct on next mount.");
1043 xfs_log_unmount(mp);
1045 xfs_uuid_unmount(mp);
1048 xfs_errortag_clearall(mp, 0);
1052 xfs_sysfs_del(&mp->m_kobj);
1056 * Determine whether modifications can proceed. The caller specifies the minimum
1057 * freeze level for which modifications should not be allowed. This allows
1058 * certain operations to proceed while the freeze sequence is in progress, if
1063 struct xfs_mount *mp,
1066 ASSERT(level > SB_UNFROZEN);
1067 if ((mp->m_super->s_writers.frozen >= level) ||
1068 XFS_FORCED_SHUTDOWN(mp) || (mp->m_flags & XFS_MOUNT_RDONLY))
1077 * Sync the superblock counters to disk.
1079 * Note this code can be called during the process of freezing, so we use the
1080 * transaction allocator that does not block when the transaction subsystem is
1081 * in its frozen state.
1084 xfs_log_sbcount(xfs_mount_t *mp)
1086 /* allow this to proceed during the freeze sequence... */
1087 if (!xfs_fs_writable(mp, SB_FREEZE_COMPLETE))
1090 xfs_icsb_sync_counters(mp, 0);
1093 * we don't need to do this if we are updating the superblock
1094 * counters on every modification.
1096 if (!xfs_sb_version_haslazysbcount(&mp->m_sb))
1099 return xfs_sync_sb(mp, true);
1104 struct xfs_mount *mp,
1107 /* deltas are +/-64, hence the large batch size of 128. */
1108 __percpu_counter_add(&mp->m_icount, delta, 128);
1109 if (percpu_counter_compare(&mp->m_icount, 0) < 0) {
1111 percpu_counter_add(&mp->m_icount, -delta);
1120 struct xfs_mount *mp,
1123 percpu_counter_add(&mp->m_ifree, delta);
1124 if (percpu_counter_compare(&mp->m_ifree, 0) < 0) {
1126 percpu_counter_add(&mp->m_ifree, -delta);
1132 * xfs_mod_incore_sb_unlocked() is a utility routine commonly used to apply
1133 * a delta to a specified field in the in-core superblock. Simply
1134 * switch on the field indicated and apply the delta to that field.
1135 * Fields are not allowed to dip below zero, so if the delta would
1136 * do this do not apply it and return EINVAL.
1138 * The m_sb_lock must be held when this routine is called.
1141 xfs_mod_incore_sb_unlocked(
1143 xfs_sb_field_t field,
1147 int scounter; /* short counter for 32 bit fields */
1148 long long lcounter; /* long counter for 64 bit fields */
1149 long long res_used, rem;
1152 * With the in-core superblock spin lock held, switch
1153 * on the indicated field. Apply the delta to the
1154 * proper field. If the fields value would dip below
1155 * 0, then do not apply the delta and return EINVAL.
1158 case XFS_SBS_ICOUNT:
1162 case XFS_SBS_FDBLOCKS:
1163 lcounter = (long long)
1164 mp->m_sb.sb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
1165 res_used = (long long)(mp->m_resblks - mp->m_resblks_avail);
1167 if (delta > 0) { /* Putting blocks back */
1168 if (res_used > delta) {
1169 mp->m_resblks_avail += delta;
1171 rem = delta - res_used;
1172 mp->m_resblks_avail = mp->m_resblks;
1175 } else { /* Taking blocks away */
1177 if (lcounter >= 0) {
1178 mp->m_sb.sb_fdblocks = lcounter +
1179 XFS_ALLOC_SET_ASIDE(mp);
1184 * We are out of blocks, use any available reserved
1185 * blocks if were allowed to.
1190 lcounter = (long long)mp->m_resblks_avail + delta;
1191 if (lcounter >= 0) {
1192 mp->m_resblks_avail = lcounter;
1195 printk_once(KERN_WARNING
1196 "Filesystem \"%s\": reserve blocks depleted! "
1197 "Consider increasing reserve pool size.",
1202 mp->m_sb.sb_fdblocks = lcounter + XFS_ALLOC_SET_ASIDE(mp);
1204 case XFS_SBS_FREXTENTS:
1205 lcounter = (long long)mp->m_sb.sb_frextents;
1210 mp->m_sb.sb_frextents = lcounter;
1212 case XFS_SBS_DBLOCKS:
1213 lcounter = (long long)mp->m_sb.sb_dblocks;
1219 mp->m_sb.sb_dblocks = lcounter;
1221 case XFS_SBS_AGCOUNT:
1222 scounter = mp->m_sb.sb_agcount;
1228 mp->m_sb.sb_agcount = scounter;
1230 case XFS_SBS_IMAX_PCT:
1231 scounter = mp->m_sb.sb_imax_pct;
1237 mp->m_sb.sb_imax_pct = scounter;
1239 case XFS_SBS_REXTSIZE:
1240 scounter = mp->m_sb.sb_rextsize;
1246 mp->m_sb.sb_rextsize = scounter;
1248 case XFS_SBS_RBMBLOCKS:
1249 scounter = mp->m_sb.sb_rbmblocks;
1255 mp->m_sb.sb_rbmblocks = scounter;
1257 case XFS_SBS_RBLOCKS:
1258 lcounter = (long long)mp->m_sb.sb_rblocks;
1264 mp->m_sb.sb_rblocks = lcounter;
1266 case XFS_SBS_REXTENTS:
1267 lcounter = (long long)mp->m_sb.sb_rextents;
1273 mp->m_sb.sb_rextents = lcounter;
1275 case XFS_SBS_REXTSLOG:
1276 scounter = mp->m_sb.sb_rextslog;
1282 mp->m_sb.sb_rextslog = scounter;
1291 * xfs_mod_incore_sb() is used to change a field in the in-core
1292 * superblock structure by the specified delta. This modification
1293 * is protected by the m_sb_lock. Just use the xfs_mod_incore_sb_unlocked()
1294 * routine to do the work.
1298 struct xfs_mount *mp,
1299 xfs_sb_field_t field,
1305 #ifdef HAVE_PERCPU_SB
1306 ASSERT(field < XFS_SBS_IFREE || field > XFS_SBS_FDBLOCKS);
1309 spin_lock(&mp->m_sb_lock);
1310 status = xfs_mod_incore_sb_unlocked(mp, field, delta, rsvd);
1311 spin_unlock(&mp->m_sb_lock);
1317 * Change more than one field in the in-core superblock structure at a time.
1319 * The fields and changes to those fields are specified in the array of
1320 * xfs_mod_sb structures passed in. Either all of the specified deltas
1321 * will be applied or none of them will. If any modified field dips below 0,
1322 * then all modifications will be backed out and EINVAL will be returned.
1324 * Note that this function may not be used for the superblock values that
1325 * are tracked with the in-memory per-cpu counters - a direct call to
1326 * xfs_icsb_modify_counters is required for these.
1329 xfs_mod_incore_sb_batch(
1330 struct xfs_mount *mp,
1339 * Loop through the array of mod structures and apply each individually.
1340 * If any fail, then back out all those which have already been applied.
1341 * Do all of this within the scope of the m_sb_lock so that all of the
1342 * changes will be atomic.
1344 spin_lock(&mp->m_sb_lock);
1345 for (msbp = msb; msbp < (msb + nmsb); msbp++) {
1346 ASSERT(msbp->msb_field < XFS_SBS_ICOUNT ||
1347 msbp->msb_field > XFS_SBS_FDBLOCKS);
1349 error = xfs_mod_incore_sb_unlocked(mp, msbp->msb_field,
1350 msbp->msb_delta, rsvd);
1354 spin_unlock(&mp->m_sb_lock);
1358 while (--msbp >= msb) {
1359 error = xfs_mod_incore_sb_unlocked(mp, msbp->msb_field,
1360 -msbp->msb_delta, rsvd);
1363 spin_unlock(&mp->m_sb_lock);
1368 * xfs_getsb() is called to obtain the buffer for the superblock.
1369 * The buffer is returned locked and read in from disk.
1370 * The buffer should be released with a call to xfs_brelse().
1372 * If the flags parameter is BUF_TRYLOCK, then we'll only return
1373 * the superblock buffer if it can be locked without sleeping.
1374 * If it can't then we'll return NULL.
1378 struct xfs_mount *mp,
1381 struct xfs_buf *bp = mp->m_sb_bp;
1383 if (!xfs_buf_trylock(bp)) {
1384 if (flags & XBF_TRYLOCK)
1390 ASSERT(XFS_BUF_ISDONE(bp));
1395 * Used to free the superblock along various error paths.
1399 struct xfs_mount *mp)
1401 struct xfs_buf *bp = mp->m_sb_bp;
1409 * If the underlying (data/log/rt) device is readonly, there are some
1410 * operations that cannot proceed.
1413 xfs_dev_is_read_only(
1414 struct xfs_mount *mp,
1417 if (xfs_readonly_buftarg(mp->m_ddev_targp) ||
1418 xfs_readonly_buftarg(mp->m_logdev_targp) ||
1419 (mp->m_rtdev_targp && xfs_readonly_buftarg(mp->m_rtdev_targp))) {
1420 xfs_notice(mp, "%s required on read-only device.", message);
1421 xfs_notice(mp, "write access unavailable, cannot proceed.");
1427 #ifdef HAVE_PERCPU_SB
1429 * Per-cpu incore superblock counters
1431 * Simple concept, difficult implementation
1433 * Basically, replace the incore superblock counters with a distributed per cpu
1434 * counter for contended fields (e.g. free block count).
1436 * Difficulties arise in that the incore sb is used for ENOSPC checking, and
1437 * hence needs to be accurately read when we are running low on space. Hence
1438 * there is a method to enable and disable the per-cpu counters based on how
1439 * much "stuff" is available in them.
1441 * Basically, a counter is enabled if there is enough free resource to justify
1442 * running a per-cpu fast-path. If the per-cpu counter runs out (i.e. a local
1443 * ENOSPC), then we disable the counters to synchronise all callers and
1444 * re-distribute the available resources.
1446 * If, once we redistributed the available resources, we still get a failure,
1447 * we disable the per-cpu counter and go through the slow path.
1449 * The slow path is the current xfs_mod_incore_sb() function. This means that
1450 * when we disable a per-cpu counter, we need to drain its resources back to
1451 * the global superblock. We do this after disabling the counter to prevent
1452 * more threads from queueing up on the counter.
1454 * Essentially, this means that we still need a lock in the fast path to enable
1455 * synchronisation between the global counters and the per-cpu counters. This
1456 * is not a problem because the lock will be local to a CPU almost all the time
1457 * and have little contention except when we get to ENOSPC conditions.
1459 * Basically, this lock becomes a barrier that enables us to lock out the fast
1460 * path while we do things like enabling and disabling counters and
1461 * synchronising the counters.
1465 * 1. m_sb_lock before picking up per-cpu locks
1466 * 2. per-cpu locks always picked up via for_each_online_cpu() order
1467 * 3. accurate counter sync requires m_sb_lock + per cpu locks
1468 * 4. modifying per-cpu counters requires holding per-cpu lock
1469 * 5. modifying global counters requires holding m_sb_lock
1470 * 6. enabling or disabling a counter requires holding the m_sb_lock
1471 * and _none_ of the per-cpu locks.
1473 * Disabled counters are only ever re-enabled by a balance operation
1474 * that results in more free resources per CPU than a given threshold.
1475 * To ensure counters don't remain disabled, they are rebalanced when
1476 * the global resource goes above a higher threshold (i.e. some hysteresis
1477 * is present to prevent thrashing).
1480 #ifdef CONFIG_HOTPLUG_CPU
1482 * hot-plug CPU notifier support.
1484 * We need a notifier per filesystem as we need to be able to identify
1485 * the filesystem to balance the counters out. This is achieved by
1486 * having a notifier block embedded in the xfs_mount_t and doing pointer
1487 * magic to get the mount pointer from the notifier block address.
1490 xfs_icsb_cpu_notify(
1491 struct notifier_block *nfb,
1492 unsigned long action,
1495 xfs_icsb_cnts_t *cntp;
1498 mp = (xfs_mount_t *)container_of(nfb, xfs_mount_t, m_icsb_notifier);
1499 cntp = (xfs_icsb_cnts_t *)
1500 per_cpu_ptr(mp->m_sb_cnts, (unsigned long)hcpu);
1502 case CPU_UP_PREPARE:
1503 case CPU_UP_PREPARE_FROZEN:
1504 /* Easy Case - initialize the area and locks, and
1505 * then rebalance when online does everything else for us. */
1506 memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
1509 case CPU_ONLINE_FROZEN:
1511 xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, 0);
1512 xfs_icsb_unlock(mp);
1515 case CPU_DEAD_FROZEN:
1516 /* Disable all the counters, then fold the dead cpu's
1517 * count into the total on the global superblock and
1518 * re-enable the counters. */
1520 spin_lock(&mp->m_sb_lock);
1521 xfs_icsb_disable_counter(mp, XFS_SBS_FDBLOCKS);
1523 mp->m_sb.sb_fdblocks += cntp->icsb_fdblocks;
1525 memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
1527 xfs_icsb_balance_counter_locked(mp, XFS_SBS_FDBLOCKS, 0);
1528 spin_unlock(&mp->m_sb_lock);
1529 xfs_icsb_unlock(mp);
1535 #endif /* CONFIG_HOTPLUG_CPU */
1538 xfs_icsb_init_counters(
1541 xfs_icsb_cnts_t *cntp;
1545 error = percpu_counter_init(&mp->m_icount, 0, GFP_KERNEL);
1549 error = percpu_counter_init(&mp->m_ifree, 0, GFP_KERNEL);
1553 mp->m_sb_cnts = alloc_percpu(xfs_icsb_cnts_t);
1554 if (!mp->m_sb_cnts) {
1559 for_each_online_cpu(i) {
1560 cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
1561 memset(cntp, 0, sizeof(xfs_icsb_cnts_t));
1564 mutex_init(&mp->m_icsb_mutex);
1567 * start with all counters disabled so that the
1568 * initial balance kicks us off correctly
1570 mp->m_icsb_counters = -1;
1572 #ifdef CONFIG_HOTPLUG_CPU
1573 mp->m_icsb_notifier.notifier_call = xfs_icsb_cpu_notify;
1574 mp->m_icsb_notifier.priority = 0;
1575 register_hotcpu_notifier(&mp->m_icsb_notifier);
1576 #endif /* CONFIG_HOTPLUG_CPU */
1581 percpu_counter_destroy(&mp->m_ifree);
1583 percpu_counter_destroy(&mp->m_icount);
1588 xfs_icsb_reinit_counters(
1591 percpu_counter_set(&mp->m_icount, mp->m_sb.sb_icount);
1592 percpu_counter_set(&mp->m_ifree, mp->m_sb.sb_ifree);
1596 * start with all counters disabled so that the
1597 * initial balance kicks us off correctly
1599 mp->m_icsb_counters = -1;
1600 xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, 0);
1601 xfs_icsb_unlock(mp);
1605 xfs_icsb_destroy_counters(
1608 if (mp->m_sb_cnts) {
1609 unregister_hotcpu_notifier(&mp->m_icsb_notifier);
1610 free_percpu(mp->m_sb_cnts);
1613 percpu_counter_destroy(&mp->m_icount);
1614 percpu_counter_destroy(&mp->m_ifree);
1616 mutex_destroy(&mp->m_icsb_mutex);
1621 xfs_icsb_cnts_t *icsbp)
1623 while (test_and_set_bit(XFS_ICSB_FLAG_LOCK, &icsbp->icsb_flags)) {
1629 xfs_icsb_unlock_cntr(
1630 xfs_icsb_cnts_t *icsbp)
1632 clear_bit(XFS_ICSB_FLAG_LOCK, &icsbp->icsb_flags);
1637 xfs_icsb_lock_all_counters(
1640 xfs_icsb_cnts_t *cntp;
1643 for_each_online_cpu(i) {
1644 cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
1645 xfs_icsb_lock_cntr(cntp);
1650 xfs_icsb_unlock_all_counters(
1653 xfs_icsb_cnts_t *cntp;
1656 for_each_online_cpu(i) {
1657 cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
1658 xfs_icsb_unlock_cntr(cntp);
1665 xfs_icsb_cnts_t *cnt,
1668 xfs_icsb_cnts_t *cntp;
1671 memset(cnt, 0, sizeof(xfs_icsb_cnts_t));
1673 if (!(flags & XFS_ICSB_LAZY_COUNT))
1674 xfs_icsb_lock_all_counters(mp);
1676 for_each_online_cpu(i) {
1677 cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
1678 cnt->icsb_fdblocks += cntp->icsb_fdblocks;
1681 if (!(flags & XFS_ICSB_LAZY_COUNT))
1682 xfs_icsb_unlock_all_counters(mp);
1686 xfs_icsb_counter_disabled(
1688 xfs_sb_field_t field)
1690 ASSERT(field == XFS_SBS_FDBLOCKS);
1691 return test_bit(field, &mp->m_icsb_counters);
1695 xfs_icsb_disable_counter(
1697 xfs_sb_field_t field)
1699 xfs_icsb_cnts_t cnt;
1701 ASSERT(field == XFS_SBS_FDBLOCKS);
1704 * If we are already disabled, then there is nothing to do
1705 * here. We check before locking all the counters to avoid
1706 * the expensive lock operation when being called in the
1707 * slow path and the counter is already disabled. This is
1708 * safe because the only time we set or clear this state is under
1711 if (xfs_icsb_counter_disabled(mp, field))
1714 xfs_icsb_lock_all_counters(mp);
1715 if (!test_and_set_bit(field, &mp->m_icsb_counters)) {
1716 /* drain back to superblock */
1718 xfs_icsb_count(mp, &cnt, XFS_ICSB_LAZY_COUNT);
1720 case XFS_SBS_FDBLOCKS:
1721 mp->m_sb.sb_fdblocks = cnt.icsb_fdblocks;
1728 xfs_icsb_unlock_all_counters(mp);
1732 xfs_icsb_enable_counter(
1734 xfs_sb_field_t field,
1738 xfs_icsb_cnts_t *cntp;
1741 ASSERT(field == XFS_SBS_FDBLOCKS);
1743 xfs_icsb_lock_all_counters(mp);
1744 for_each_online_cpu(i) {
1745 cntp = per_cpu_ptr(mp->m_sb_cnts, i);
1747 case XFS_SBS_FDBLOCKS:
1748 cntp->icsb_fdblocks = count + resid;
1756 clear_bit(field, &mp->m_icsb_counters);
1757 xfs_icsb_unlock_all_counters(mp);
1761 xfs_icsb_sync_counters_locked(
1765 xfs_icsb_cnts_t cnt;
1767 xfs_icsb_count(mp, &cnt, flags);
1769 if (!xfs_icsb_counter_disabled(mp, XFS_SBS_FDBLOCKS))
1770 mp->m_sb.sb_fdblocks = cnt.icsb_fdblocks;
1774 * Accurate update of per-cpu counters to incore superblock
1777 xfs_icsb_sync_counters(
1781 spin_lock(&mp->m_sb_lock);
1782 xfs_icsb_sync_counters_locked(mp, flags);
1783 spin_unlock(&mp->m_sb_lock);
1787 * Balance and enable/disable counters as necessary.
1789 * Thresholds for re-enabling counters are somewhat magic. inode counts are
1790 * chosen to be the same number as single on disk allocation chunk per CPU, and
1791 * free blocks is something far enough zero that we aren't going thrash when we
1792 * get near ENOSPC. We also need to supply a minimum we require per cpu to
1793 * prevent looping endlessly when xfs_alloc_space asks for more than will
1794 * be distributed to a single CPU but each CPU has enough blocks to be
1797 * Note that we can be called when counters are already disabled.
1798 * xfs_icsb_disable_counter() optimises the counter locking in this case to
1799 * prevent locking every per-cpu counter needlessly.
1802 #define XFS_ICSB_INO_CNTR_REENABLE (uint64_t)64
1803 #define XFS_ICSB_FDBLK_CNTR_REENABLE(mp) \
1804 (uint64_t)(512 + XFS_ALLOC_SET_ASIDE(mp))
1806 xfs_icsb_balance_counter_locked(
1808 xfs_sb_field_t field,
1811 uint64_t count, resid;
1812 int weight = num_online_cpus();
1813 uint64_t min = (uint64_t)min_per_cpu;
1815 /* disable counter and sync counter */
1816 xfs_icsb_disable_counter(mp, field);
1818 /* update counters - first CPU gets residual*/
1820 case XFS_SBS_FDBLOCKS:
1821 count = mp->m_sb.sb_fdblocks;
1822 resid = do_div(count, weight);
1823 if (count < max(min, XFS_ICSB_FDBLK_CNTR_REENABLE(mp)))
1828 count = resid = 0; /* quiet, gcc */
1832 xfs_icsb_enable_counter(mp, field, count, resid);
1836 xfs_icsb_balance_counter(
1838 xfs_sb_field_t fields,
1841 spin_lock(&mp->m_sb_lock);
1842 xfs_icsb_balance_counter_locked(mp, fields, min_per_cpu);
1843 spin_unlock(&mp->m_sb_lock);
1847 xfs_icsb_modify_counters(
1849 xfs_sb_field_t field,
1853 xfs_icsb_cnts_t *icsbp;
1854 long long lcounter; /* long counter for 64 bit fields */
1860 icsbp = this_cpu_ptr(mp->m_sb_cnts);
1863 * if the counter is disabled, go to slow path
1865 if (unlikely(xfs_icsb_counter_disabled(mp, field)))
1867 xfs_icsb_lock_cntr(icsbp);
1868 if (unlikely(xfs_icsb_counter_disabled(mp, field))) {
1869 xfs_icsb_unlock_cntr(icsbp);
1874 case XFS_SBS_FDBLOCKS:
1875 BUG_ON((mp->m_resblks - mp->m_resblks_avail) != 0);
1877 lcounter = icsbp->icsb_fdblocks - XFS_ALLOC_SET_ASIDE(mp);
1879 if (unlikely(lcounter < 0))
1880 goto balance_counter;
1881 icsbp->icsb_fdblocks = lcounter + XFS_ALLOC_SET_ASIDE(mp);
1887 xfs_icsb_unlock_cntr(icsbp);
1895 * serialise with a mutex so we don't burn lots of cpu on
1896 * the superblock lock. We still need to hold the superblock
1897 * lock, however, when we modify the global structures.
1902 * Now running atomically.
1904 * If the counter is enabled, someone has beaten us to rebalancing.
1905 * Drop the lock and try again in the fast path....
1907 if (!(xfs_icsb_counter_disabled(mp, field))) {
1908 xfs_icsb_unlock(mp);
1913 * The counter is currently disabled. Because we are
1914 * running atomically here, we know a rebalance cannot
1915 * be in progress. Hence we can go straight to operating
1916 * on the global superblock. We do not call xfs_mod_incore_sb()
1917 * here even though we need to get the m_sb_lock. Doing so
1918 * will cause us to re-enter this function and deadlock.
1919 * Hence we get the m_sb_lock ourselves and then call
1920 * xfs_mod_incore_sb_unlocked() as the unlocked path operates
1921 * directly on the global counters.
1923 spin_lock(&mp->m_sb_lock);
1924 ret = xfs_mod_incore_sb_unlocked(mp, field, delta, rsvd);
1925 spin_unlock(&mp->m_sb_lock);
1928 * Now that we've modified the global superblock, we
1929 * may be able to re-enable the distributed counters
1930 * (e.g. lots of space just got freed). After that
1934 xfs_icsb_balance_counter(mp, field, 0);
1935 xfs_icsb_unlock(mp);
1939 xfs_icsb_unlock_cntr(icsbp);
1943 * We may have multiple threads here if multiple per-cpu
1944 * counters run dry at the same time. This will mean we can
1945 * do more balances than strictly necessary but it is not
1946 * the common slowpath case.
1951 * running atomically.
1953 * This will leave the counter in the correct state for future
1954 * accesses. After the rebalance, we simply try again and our retry
1955 * will either succeed through the fast path or slow path without
1956 * another balance operation being required.
1958 xfs_icsb_balance_counter(mp, field, delta);
1959 xfs_icsb_unlock(mp);