diff options
Diffstat (limited to 'fs/xfs/xfs_mount.c')
| -rw-r--r-- | fs/xfs/xfs_mount.c | 516 |
1 files changed, 1 insertions, 515 deletions
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c index 767c09a5d3ff..05b392e35e35 100644 --- a/fs/xfs/xfs_mount.c +++ b/fs/xfs/xfs_mount.c @@ -43,18 +43,6 @@ #include "xfs_sysfs.h" -#ifdef HAVE_PERCPU_SB -STATIC void xfs_icsb_balance_counter(xfs_mount_t *, xfs_sb_field_t, - int); -STATIC void xfs_icsb_balance_counter_locked(xfs_mount_t *, xfs_sb_field_t, - int); -STATIC void xfs_icsb_disable_counter(xfs_mount_t *, xfs_sb_field_t); -#else - -#define xfs_icsb_balance_counter(mp, a, b) do { } while (0) -#define xfs_icsb_balance_counter_locked(mp, a, b) do { } while (0) -#endif - static DEFINE_MUTEX(xfs_uuid_table_mutex); static int xfs_uuid_table_size; static uuid_t *xfs_uuid_table; @@ -347,8 +335,7 @@ reread: goto reread; } - /* Initialize per-cpu counters */ - xfs_icsb_reinit_counters(mp); + xfs_reinit_percpu_counters(mp); /* no need to be quiet anymore, so reset the buf ops */ bp->b_ops = &xfs_sb_buf_ops; @@ -1087,8 +1074,6 @@ xfs_log_sbcount(xfs_mount_t *mp) if (!xfs_fs_writable(mp, SB_FREEZE_COMPLETE)) return 0; - xfs_icsb_sync_counters(mp, 0); - /* * we don't need to do this if we are updating the superblock * counters on every modification. @@ -1466,502 +1451,3 @@ xfs_dev_is_read_only( } return 0; } - -#ifdef HAVE_PERCPU_SB -/* - * Per-cpu incore superblock counters - * - * Simple concept, difficult implementation - * - * Basically, replace the incore superblock counters with a distributed per cpu - * counter for contended fields (e.g. free block count). - * - * Difficulties arise in that the incore sb is used for ENOSPC checking, and - * hence needs to be accurately read when we are running low on space. Hence - * there is a method to enable and disable the per-cpu counters based on how - * much "stuff" is available in them. - * - * Basically, a counter is enabled if there is enough free resource to justify - * running a per-cpu fast-path. If the per-cpu counter runs out (i.e. a local - * ENOSPC), then we disable the counters to synchronise all callers and - * re-distribute the available resources. - * - * If, once we redistributed the available resources, we still get a failure, - * we disable the per-cpu counter and go through the slow path. - * - * The slow path is the current xfs_mod_incore_sb() function. This means that - * when we disable a per-cpu counter, we need to drain its resources back to - * the global superblock. We do this after disabling the counter to prevent - * more threads from queueing up on the counter. - * - * Essentially, this means that we still need a lock in the fast path to enable - * synchronisation between the global counters and the per-cpu counters. This - * is not a problem because the lock will be local to a CPU almost all the time - * and have little contention except when we get to ENOSPC conditions. - * - * Basically, this lock becomes a barrier that enables us to lock out the fast - * path while we do things like enabling and disabling counters and - * synchronising the counters. - * - * Locking rules: - * - * 1. m_sb_lock before picking up per-cpu locks - * 2. per-cpu locks always picked up via for_each_online_cpu() order - * 3. accurate counter sync requires m_sb_lock + per cpu locks - * 4. modifying per-cpu counters requires holding per-cpu lock - * 5. modifying global counters requires holding m_sb_lock - * 6. enabling or disabling a counter requires holding the m_sb_lock - * and _none_ of the per-cpu locks. - * - * Disabled counters are only ever re-enabled by a balance operation - * that results in more free resources per CPU than a given threshold. - * To ensure counters don't remain disabled, they are rebalanced when - * the global resource goes above a higher threshold (i.e. some hysteresis - * is present to prevent thrashing). - */ - -#ifdef CONFIG_HOTPLUG_CPU -/* - * hot-plug CPU notifier support. - * - * We need a notifier per filesystem as we need to be able to identify - * the filesystem to balance the counters out. This is achieved by - * having a notifier block embedded in the xfs_mount_t and doing pointer - * magic to get the mount pointer from the notifier block address. - */ -STATIC int -xfs_icsb_cpu_notify( - struct notifier_block *nfb, - unsigned long action, - void *hcpu) -{ - xfs_icsb_cnts_t *cntp; - xfs_mount_t *mp; - - mp = (xfs_mount_t *)container_of(nfb, xfs_mount_t, m_icsb_notifier); - cntp = (xfs_icsb_cnts_t *) - per_cpu_ptr(mp->m_sb_cnts, (unsigned long)hcpu); - switch (action) { - case CPU_UP_PREPARE: - case CPU_UP_PREPARE_FROZEN: - /* Easy Case - initialize the area and locks, and - * then rebalance when online does everything else for us. */ - memset(cntp, 0, sizeof(xfs_icsb_cnts_t)); - break; - case CPU_ONLINE: - case CPU_ONLINE_FROZEN: - xfs_icsb_lock(mp); - xfs_icsb_unlock(mp); - break; - case CPU_DEAD: - case CPU_DEAD_FROZEN: - /* Disable all the counters, then fold the dead cpu's - * count into the total on the global superblock and - * re-enable the counters. */ - xfs_icsb_lock(mp); - spin_lock(&mp->m_sb_lock); - - memset(cntp, 0, sizeof(xfs_icsb_cnts_t)); - - spin_unlock(&mp->m_sb_lock); - xfs_icsb_unlock(mp); - break; - } - - return NOTIFY_OK; -} -#endif /* CONFIG_HOTPLUG_CPU */ - -int -xfs_icsb_init_counters( - xfs_mount_t *mp) -{ - xfs_icsb_cnts_t *cntp; - int error; - int i; - - error = percpu_counter_init(&mp->m_icount, 0, GFP_KERNEL); - if (error) - return error; - - error = percpu_counter_init(&mp->m_ifree, 0, GFP_KERNEL); - if (error) - goto free_icount; - - error = percpu_counter_init(&mp->m_fdblocks, 0, GFP_KERNEL); - if (error) - goto free_ifree; - - mp->m_sb_cnts = alloc_percpu(xfs_icsb_cnts_t); - if (!mp->m_sb_cnts) { - error = -ENOMEM; - goto free_fdblocks; - } - - for_each_online_cpu(i) { - cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i); - memset(cntp, 0, sizeof(xfs_icsb_cnts_t)); - } - - mutex_init(&mp->m_icsb_mutex); - - /* - * start with all counters disabled so that the - * initial balance kicks us off correctly - */ - mp->m_icsb_counters = -1; - -#ifdef CONFIG_HOTPLUG_CPU - mp->m_icsb_notifier.notifier_call = xfs_icsb_cpu_notify; - mp->m_icsb_notifier.priority = 0; - register_hotcpu_notifier(&mp->m_icsb_notifier); -#endif /* CONFIG_HOTPLUG_CPU */ - - return 0; - -free_fdblocks: - percpu_counter_destroy(&mp->m_fdblocks); -free_ifree: - percpu_counter_destroy(&mp->m_ifree); -free_icount: - percpu_counter_destroy(&mp->m_icount); - return error; -} - -void -xfs_icsb_reinit_counters( - xfs_mount_t *mp) -{ - percpu_counter_set(&mp->m_icount, mp->m_sb.sb_icount); - percpu_counter_set(&mp->m_ifree, mp->m_sb.sb_ifree); - percpu_counter_set(&mp->m_fdblocks, mp->m_sb.sb_fdblocks); - - xfs_icsb_lock(mp); - /* - * start with all counters disabled so that the - * initial balance kicks us off correctly - */ - mp->m_icsb_counters = -1; - xfs_icsb_unlock(mp); -} - -void -xfs_icsb_destroy_counters( - xfs_mount_t *mp) -{ - if (mp->m_sb_cnts) { - unregister_hotcpu_notifier(&mp->m_icsb_notifier); - free_percpu(mp->m_sb_cnts); - } - - percpu_counter_destroy(&mp->m_icount); - percpu_counter_destroy(&mp->m_ifree); - percpu_counter_destroy(&mp->m_fdblocks); - - mutex_destroy(&mp->m_icsb_mutex); -} - -STATIC void -xfs_icsb_lock_cntr( - xfs_icsb_cnts_t *icsbp) -{ - while (test_and_set_bit(XFS_ICSB_FLAG_LOCK, &icsbp->icsb_flags)) { - ndelay(1000); - } -} - -STATIC void -xfs_icsb_unlock_cntr( - xfs_icsb_cnts_t *icsbp) -{ - clear_bit(XFS_ICSB_FLAG_LOCK, &icsbp->icsb_flags); -} - - -STATIC void -xfs_icsb_lock_all_counters( - xfs_mount_t *mp) -{ - xfs_icsb_cnts_t *cntp; - int i; - - for_each_online_cpu(i) { - cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i); - xfs_icsb_lock_cntr(cntp); - } -} - -STATIC void -xfs_icsb_unlock_all_counters( - xfs_mount_t *mp) -{ - xfs_icsb_cnts_t *cntp; - int i; - - for_each_online_cpu(i) { - cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i); - xfs_icsb_unlock_cntr(cntp); - } -} - -STATIC void -xfs_icsb_count( - xfs_mount_t *mp, - xfs_icsb_cnts_t *cnt, - int flags) -{ - memset(cnt, 0, sizeof(xfs_icsb_cnts_t)); - - if (!(flags & XFS_ICSB_LAZY_COUNT)) - xfs_icsb_lock_all_counters(mp); - - - if (!(flags & XFS_ICSB_LAZY_COUNT)) - xfs_icsb_unlock_all_counters(mp); -} - -STATIC int -xfs_icsb_counter_disabled( - xfs_mount_t *mp, - xfs_sb_field_t field) -{ - return test_bit(field, &mp->m_icsb_counters); -} - -STATIC void -xfs_icsb_disable_counter( - xfs_mount_t *mp, - xfs_sb_field_t field) -{ - xfs_icsb_cnts_t cnt; - - /* - * If we are already disabled, then there is nothing to do - * here. We check before locking all the counters to avoid - * the expensive lock operation when being called in the - * slow path and the counter is already disabled. This is - * safe because the only time we set or clear this state is under - * the m_icsb_mutex. - */ - if (xfs_icsb_counter_disabled(mp, field)) - return; - - xfs_icsb_lock_all_counters(mp); - if (!test_and_set_bit(field, &mp->m_icsb_counters)) { - /* drain back to superblock */ - - xfs_icsb_count(mp, &cnt, XFS_ICSB_LAZY_COUNT); - switch(field) { - default: - BUG(); - } - } - - xfs_icsb_unlock_all_counters(mp); -} - -STATIC void -xfs_icsb_enable_counter( - xfs_mount_t *mp, - xfs_sb_field_t field, - uint64_t count, - uint64_t resid) -{ - int i; - - xfs_icsb_lock_all_counters(mp); - for_each_online_cpu(i) { - switch (field) { - default: - BUG(); - break; - } - resid = 0; - } - clear_bit(field, &mp->m_icsb_counters); - xfs_icsb_unlock_all_counters(mp); -} - -void -xfs_icsb_sync_counters_locked( - xfs_mount_t *mp, - int flags) -{ - xfs_icsb_cnts_t cnt; - - xfs_icsb_count(mp, &cnt, flags); -} - -/* - * Accurate update of per-cpu counters to incore superblock - */ -void -xfs_icsb_sync_counters( - xfs_mount_t *mp, - int flags) -{ - spin_lock(&mp->m_sb_lock); - xfs_icsb_sync_counters_locked(mp, flags); - spin_unlock(&mp->m_sb_lock); -} - -/* - * Balance and enable/disable counters as necessary. - * - * Thresholds for re-enabling counters are somewhat magic. inode counts are - * chosen to be the same number as single on disk allocation chunk per CPU, and - * free blocks is something far enough zero that we aren't going thrash when we - * get near ENOSPC. We also need to supply a minimum we require per cpu to - * prevent looping endlessly when xfs_alloc_space asks for more than will - * be distributed to a single CPU but each CPU has enough blocks to be - * reenabled. - * - * Note that we can be called when counters are already disabled. - * xfs_icsb_disable_counter() optimises the counter locking in this case to - * prevent locking every per-cpu counter needlessly. - */ - -#define XFS_ICSB_INO_CNTR_REENABLE (uint64_t)64 -#define XFS_ICSB_FDBLK_CNTR_REENABLE(mp) \ - (uint64_t)(512 + XFS_ALLOC_SET_ASIDE(mp)) -STATIC void -xfs_icsb_balance_counter_locked( - xfs_mount_t *mp, - xfs_sb_field_t field, - int min_per_cpu) -{ - uint64_t count, resid; - - /* disable counter and sync counter */ - xfs_icsb_disable_counter(mp, field); - - /* update counters - first CPU gets residual*/ - switch (field) { - default: - BUG(); - count = resid = 0; /* quiet, gcc */ - break; - } - - xfs_icsb_enable_counter(mp, field, count, resid); -} - -STATIC void -xfs_icsb_balance_counter( - xfs_mount_t *mp, - xfs_sb_field_t fields, - int min_per_cpu) -{ - spin_lock(&mp->m_sb_lock); - xfs_icsb_balance_counter_locked(mp, fields, min_per_cpu); - spin_unlock(&mp->m_sb_lock); -} - -int -xfs_icsb_modify_counters( - xfs_mount_t *mp, - xfs_sb_field_t field, - int64_t delta, - int rsvd) -{ - xfs_icsb_cnts_t *icsbp; - int ret = 0; - - might_sleep(); -again: - preempt_disable(); - icsbp = this_cpu_ptr(mp->m_sb_cnts); - - /* - * if the counter is disabled, go to slow path - */ - if (unlikely(xfs_icsb_counter_disabled(mp, field))) - goto slow_path; - xfs_icsb_lock_cntr(icsbp); - if (unlikely(xfs_icsb_counter_disabled(mp, field))) { - xfs_icsb_unlock_cntr(icsbp); - goto slow_path; - } - - switch (field) { - default: - BUG(); - goto balance_counter; /* be still, gcc */ - } - xfs_icsb_unlock_cntr(icsbp); - preempt_enable(); - return 0; - -slow_path: - preempt_enable(); - - /* - * serialise with a mutex so we don't burn lots of cpu on - * the superblock lock. We still need to hold the superblock - * lock, however, when we modify the global structures. - */ - xfs_icsb_lock(mp); - - /* - * Now running atomically. - * - * If the counter is enabled, someone has beaten us to rebalancing. - * Drop the lock and try again in the fast path.... - */ - if (!(xfs_icsb_counter_disabled(mp, field))) { - xfs_icsb_unlock(mp); - goto again; - } - - /* - * The counter is currently disabled. Because we are - * running atomically here, we know a rebalance cannot - * be in progress. Hence we can go straight to operating - * on the global superblock. We do not call xfs_mod_incore_sb() - * here even though we need to get the m_sb_lock. Doing so - * will cause us to re-enter this function and deadlock. - * Hence we get the m_sb_lock ourselves and then call - * xfs_mod_incore_sb_unlocked() as the unlocked path operates - * directly on the global counters. - */ - spin_lock(&mp->m_sb_lock); - ret = xfs_mod_incore_sb_unlocked(mp, field, delta, rsvd); - spin_unlock(&mp->m_sb_lock); - - /* - * Now that we've modified the global superblock, we - * may be able to re-enable the distributed counters - * (e.g. lots of space just got freed). After that - * we are done. - */ - if (ret != -ENOSPC) - xfs_icsb_balance_counter(mp, field, 0); - xfs_icsb_unlock(mp); - return ret; - -balance_counter: - xfs_icsb_unlock_cntr(icsbp); - preempt_enable(); - - /* - * We may have multiple threads here if multiple per-cpu - * counters run dry at the same time. This will mean we can - * do more balances than strictly necessary but it is not - * the common slowpath case. - */ - xfs_icsb_lock(mp); - - /* - * running atomically. - * - * This will leave the counter in the correct state for future - * accesses. After the rebalance, we simply try again and our retry - * will either succeed through the fast path or slow path without - * another balance operation being required. - */ - xfs_icsb_balance_counter(mp, field, delta); - xfs_icsb_unlock(mp); - goto again; -} - -#endif |
