litmus-rt.git - The LITMUS^RT kernel.

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author	Tejun Heo <htejun@gmail.com>	2006-11-15 20:50:50 -0500
committer	Tejun Heo <htejun@gmail.com>	2006-12-03 03:56:23 -0500
commit	3d3cca37559e3ab2b574eda11ed5207ccdb8980a (patch)
tree	f3f3794cd7d68c681c69e85d50345a22aecc5eac /drivers/ata
parent	8070217d301d0ceab7d0c255d7b9d796256d37e7 (diff)

[PATCH] libata: implement ATA_FLAG_SETXFER_POLLING and use it in pata_via, take #2

This patch implements ATA_FLAG_SETXFER_POLLING and use in pata_via. If this flag is set, transfer mode setting performed by polling not by interrupt. This should help those controllers which raise interrupt before the command is actually complete on SETXFER. Rationale for this approach. * uses existing facility and relatively simple * no busy sleep in the interrupt handler * updating drivers is easy While at it, kill now unused flag ATA_FLAG_SRST in pata_via. Signed-off-by: Tejun Heo <htejun@gmail.com>

Diffstat (limited to 'drivers/ata')

-rw-r--r--

drivers/ata/libata-core.c

-rw-r--r--

drivers/ata/pata_via.c

2 files changed, 14 insertions, 6 deletions

                 }
         }
+        /* Some controllers show flaky interrupt behavior after
+         * setting xfer mode.  Use polling instead.
+         */
+        if (unlikely(qc->tf.command == ATA_CMD_SET_FEATURES &&
+                     qc->tf.feature == SETFEATURES_XFER) &&
+            (ap->flags & ATA_FLAG_SETXFER_POLLING))
+                qc->tf.flags |= ATA_TFLAG_POLLING;
         /* select the device */
         ata_dev_select(ap, qc->dev->devno, 1, 0);
         /* Early VIA without UDMA support */
         static struct ata_port_info via_mwdma_info = {
                 .sht = &via_sht,
-                .flags = ATA_FLAG_SLAVE_POSS | ATA_FLAG_SRST,
+                .flags = ATA_FLAG_SLAVE_POSS | ATA_FLAG_SETXFER_POLLING,
                 .pio_mask = 0x1f,
                 .mwdma_mask = 0x07,
                 .port_ops = &via_port_ops
         /* Ditto with IRQ masking required */
         static struct ata_port_info via_mwdma_info_borked = {
                 .sht = &via_sht,
-                .flags = ATA_FLAG_SLAVE_POSS | ATA_FLAG_SRST,
+                .flags = ATA_FLAG_SLAVE_POSS | ATA_FLAG_SETXFER_POLLING,
                 .pio_mask = 0x1f,
                 .mwdma_mask = 0x07,
                 .port_ops = &via_port_ops_noirq,
         /* VIA UDMA 33 devices (and borked 66) */
         static struct ata_port_info via_udma33_info = {
                 .sht = &via_sht,
-                .flags = ATA_FLAG_SLAVE_POSS | ATA_FLAG_SRST,
+                .flags = ATA_FLAG_SLAVE_POSS | ATA_FLAG_SETXFER_POLLING,
                 .pio_mask = 0x1f,
                 .mwdma_mask = 0x07,
                 .udma_mask = 0x7,
         /* VIA UDMA 66 devices */
         static struct ata_port_info via_udma66_info = {
                 .sht = &via_sht,
-                .flags = ATA_FLAG_SLAVE_POSS | ATA_FLAG_SRST,
+                .flags = ATA_FLAG_SLAVE_POSS | ATA_FLAG_SETXFER_POLLING,
                 .pio_mask = 0x1f,
                 .mwdma_mask = 0x07,
                 .udma_mask = 0x1f,
         /* VIA UDMA 100 devices */
         static struct ata_port_info via_udma100_info = {
                 .sht = &via_sht,
-                .flags = ATA_FLAG_SLAVE_POSS | ATA_FLAG_SRST,
+                .flags = ATA_FLAG_SLAVE_POSS | ATA_FLAG_SETXFER_POLLING,
                 .pio_mask = 0x1f,
                 .mwdma_mask = 0x07,
                 .udma_mask = 0x3f,
         /* UDMA133 with bad AST (All current 133) */
         static struct ata_port_info via_udma133_info = {
                 .sht = &via_sht,
-                .flags = ATA_FLAG_SLAVE_POSS | ATA_FLAG_SRST,
+                .flags = ATA_FLAG_SLAVE_POSS | ATA_FLAG_SETXFER_POLLING,
                 .pio_mask = 0x1f,
                 .mwdma_mask = 0x07,
                 .udma_mask = 0x7f,      /* FIXME: should check north bridge */

/* * fs/fs-writeback.c * * Copyright (C) 2002, Linus Torvalds. * * Contains all the functions related to writing back and waiting * upon dirty inodes against superblocks, and writing back dirty * pages against inodes. ie: data writeback. Writeout of the * inode itself is not handled here. * * 10Apr2002 Andrew Morton * Split out of fs/inode.c * Additions for address_space-based writeback */ #include <linux/kernel.h> #include <linux/module.h> #include <linux/spinlock.h> #include <linux/slab.h> #include <linux/sched.h> #include <linux/fs.h> #include <linux/mm.h> #include <linux/kthread.h> #include <linux/freezer.h> #include <linux/writeback.h> #include <linux/blkdev.h> #include <linux/backing-dev.h> #include <linux/buffer_head.h> #include <linux/tracepoint.h> #include "internal.h" /* * Passed into wb_writeback(), essentially a subset of writeback_control */ struct wb_writeback_work { long nr_pages; struct super_block *sb; enum writeback_sync_modes sync_mode; unsigned int for_kupdate:1; unsigned int range_cyclic:1; unsigned int for_background:1; struct list_head list; /* pending work list */ struct completion *done; /* set if the caller waits */ }; /* * Include the creation of the trace points after defining the * wb_writeback_work structure so that the definition remains local to this * file. */ #define CREATE_TRACE_POINTS #include <trace/events/writeback.h> /* * We don't actually have pdflush, but this one is exported though /proc... */ int nr_pdflush_threads; /** * writeback_in_progress - determine whether there is writeback in progress * @bdi: the device's backing_dev_info structure. * * Determine whether there is writeback waiting to be handled against a * backing device. */ int writeback_in_progress(struct backing_dev_info *bdi) { return test_bit(BDI_writeback_running, &bdi->state); } static inline struct backing_dev_info *inode_to_bdi(struct inode *inode) { struct super_block *sb = inode->i_sb; if (strcmp(sb->s_type->name, "bdev") == 0) return inode->i_mapping->backing_dev_info; return sb->s_bdi; } static inline struct inode *wb_inode(struct list_head *head) { return list_entry(head, struct inode, i_wb_list); } /* Wakeup flusher thread or forker thread to fork it. Requires bdi->wb_lock. */ static void bdi_wakeup_flusher(struct backing_dev_info *bdi) { if (bdi->wb.task) { wake_up_process(bdi->wb.task); } else { /* * The bdi thread isn't there, wake up the forker thread which * will create and run it. */ wake_up_process(default_backing_dev_info.wb.task); } } static void bdi_queue_work(struct backing_dev_info *bdi, struct wb_writeback_work *work) { trace_writeback_queue(bdi, work); spin_lock_bh(&bdi->wb_lock); list_add_tail(&work->list, &bdi->work_list); if (!bdi->wb.task) trace_writeback_nothread(bdi, work); bdi_wakeup_flusher(bdi); spin_unlock_bh(&bdi->wb_lock); } static void __bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages, bool range_cyclic) { struct wb_writeback_work *work; /* * This is WB_SYNC_NONE writeback, so if allocation fails just * wakeup the thread for old dirty data writeback */ work = kzalloc(sizeof(*work), GFP_ATOMIC); if (!work) { if (bdi->wb.task) { trace_writeback_nowork(bdi); wake_up_process(bdi->wb.task); } return; } work->sync_mode = WB_SYNC_NONE; work->nr_pages = nr_pages; work->range_cyclic = range_cyclic; bdi_queue_work(bdi, work); } /** * bdi_start_writeback - start writeback * @bdi: the backing device to write from * @nr_pages: the number of pages to write * * Description: * This does WB_SYNC_NONE opportunistic writeback. The IO is only * started when this function returns, we make no guarentees on * completion. Caller need not hold sb s_umount semaphore. * */ void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages) { __bdi_start_writeback(bdi, nr_pages, true); } /** * bdi_start_background_writeback - start background writeback * @bdi: the backing device to write from * * Description: * This makes sure WB_SYNC_NONE background writeback happens. When * this function returns, it is only guaranteed that for given BDI * some IO is happening if we are over background dirty threshold. * Caller need not hold sb s_umount semaphore. */ void bdi_start_background_writeback(struct backing_dev_info *bdi) { /* * We just wake up the flusher thread. It will perform background * writeback as soon as there is no other work to do. */ trace_writeback_wake_background(bdi); spin_lock_bh(&bdi->wb_lock); bdi_wakeup_flusher(bdi); spin_unlock_bh(&bdi->wb_lock); } /* * Remove the inode from the writeback list it is on. */ void inode_wb_list_del(struct inode *inode) { spin_lock(&inode_wb_list_lock); list_del_init(&inode->i_wb_list); spin_unlock(&inode_wb_list_lock); } /* * Redirty an inode: set its when-it-was dirtied timestamp and move it to the * furthest end of its superblock's dirty-inode list. * * Before stamping the inode's ->dirtied_when, we check to see whether it is * already the most-recently-dirtied inode on the b_dirty list. If that is * the case then the inode must have been redirtied while it was being written * out and we don't reset its dirtied_when. */ static void redirty_tail(struct inode *inode) { struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; assert_spin_locked(&inode_wb_list_lock); if (!list_empty(&wb->b_dirty)) { struct inode *tail; tail = wb_inode(wb->b_dirty.next); if (time_before(inode->dirtied_when, tail->dirtied_when)) inode->dirtied_when = jiffies; } list_move(&inode->i_wb_list, &wb->b_dirty); } /* * requeue inode for re-scanning after bdi->b_io list is exhausted. */ static void requeue_io(struct inode *inode) { struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; assert_spin_locked(&inode_wb_list_lock); list_move(&inode->i_wb_list, &wb->b_more_io); } static void inode_sync_complete(struct inode *inode) { /* * Prevent speculative execution through * spin_unlock(&inode_wb_list_lock); */ smp_mb(); wake_up_bit(&inode->i_state, __I_SYNC); } static bool inode_dirtied_after(struct inode *inode, unsigned long t) { bool ret = time_after(inode->dirtied_when, t); #ifndef CONFIG_64BIT /* * For inodes being constantly redirtied, dirtied_when can get stuck. * It _appears_ to be in the future, but is actually in distant past. * This test is necessary to prevent such wrapped-around relative times * from permanently stopping the whole bdi writeback. */ ret = ret && time_before_eq(inode->dirtied_when, jiffies); #endif return ret; } /* * Move expired dirty inodes from @delaying_queue to @dispatch_queue. */ static void move_expired_inodes(struct list_head *delaying_queue, struct list_head *dispatch_queue, unsigned long *older_than_this) { LIST_HEAD(tmp); struct list_head *pos, *node; struct super_block *sb = NULL; struct inode *inode; int do_sb_sort = 0; while (!list_empty(delaying_queue)) { inode = wb_inode(delaying_queue->prev); if (older_than_this && inode_dirtied_after(inode, *older_than_this)) break; if (sb && sb != inode->i_sb) do_sb_sort = 1; sb = inode->i_sb; list_move(&inode->i_wb_list, &tmp); } /* just one sb in list, splice to dispatch_queue and we're done */ if (!do_sb_sort) { list_splice(&tmp, dispatch_queue); return; } /* Move inodes from one superblock together */ while (!list_empty(&tmp)) { sb = wb_inode(tmp.prev)->i_sb; list_for_each_prev_safe(pos, node, &tmp) { inode = wb_inode(pos); if (inode->i_sb == sb) list_move(&inode->i_wb_list, dispatch_queue); } } } /* * Queue all expired dirty inodes for io, eldest first. * Before * newly dirtied b_dirty b_io b_more_io * =============> gf edc BA * After * newly dirtied b_dirty b_io b_more_io * =============> g fBAedc * | * +--> dequeue for IO */ static void queue_io(struct bdi_writeback *wb, unsigned long *older_than_this) { assert_spin_locked(&inode_wb_list_lock); list_splice_init(&wb->b_more_io, &wb->b_io); move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this); } static int write_inode(struct inode *inode, struct writeback_control *wbc) { if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) return inode->i_sb->s_op->write_inode(inode, wbc); return 0; } /* * Wait for writeback on an inode to complete. */ static void inode_wait_for_writeback(struct inode *inode) { DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC); wait_queue_head_t *wqh; wqh = bit_waitqueue(&inode->i_state, __I_SYNC); while (inode->i_state & I_SYNC) { spin_unlock(&inode->i_lock); spin_unlock(&inode_wb_list_lock); __wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE); spin_lock(&inode_wb_list_lock); spin_lock(&inode->i_lock); } } /* * Write out an inode's dirty pages. Called under inode_wb_list_lock and * inode->i_lock. Either the caller has an active reference on the inode or * the inode has I_WILL_FREE set. * * If `wait' is set, wait on the writeout. * * The whole writeout design is quite complex and fragile. We want to avoid * starvation of particular inodes when others are being redirtied, prevent * livelocks, etc. */ static int writeback_single_inode(struct inode *inode, struct writeback_control *wbc) { struct address_space *mapping = inode->i_mapping; unsigned dirty; int ret; assert_spin_locked(&inode_wb_list_lock); assert_spin_locked(&inode->i_lock); if (!atomic_read(&inode->i_count)) WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); else WARN_ON(inode->i_state & I_WILL_FREE); if (inode->i_state & I_SYNC) { /* * If this inode is locked for writeback and we are not doing * writeback-for-data-integrity, move it to b_more_io so that * writeback can proceed with the other inodes on s_io. * * We'll have another go at writing back this inode when we * completed a full scan of b_io. */ if (wbc->sync_mode != WB_SYNC_ALL) { requeue_io(inode); return 0; } /* * It's a data-integrity sync. We must wait. */ inode_wait_for_writeback(inode); } BUG_ON(inode->i_state & I_SYNC); /* Set I_SYNC, reset I_DIRTY_PAGES */ inode->i_state |= I_SYNC; inode->i_state &= ~I_DIRTY_PAGES; spin_unlock(&inode->i_lock); spin_unlock(&inode_wb_list_lock); ret = do_writepages(mapping, wbc); /* * Make sure to wait on the data before writing out the metadata. * This is important for filesystems that modify metadata on data * I/O completion. */ if (wbc->sync_mode == WB_SYNC_ALL) { int err = filemap_fdatawait(mapping); if (ret == 0) ret = err; } /* * Some filesystems may redirty the inode during the writeback * due to delalloc, clear dirty metadata flags right before * write_inode() */ spin_lock(&inode->i_lock); dirty = inode->i_state & I_DIRTY; inode->i_state &= ~(I_DIRTY_SYNC | I_DIRTY_DATASYNC); spin_unlock(&inode->i_lock); /* Don't write the inode if only I_DIRTY_PAGES was set */ if (dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { int err = write_inode(inode, wbc); if (ret == 0) ret = err; } spin_lock(&inode_wb_list_lock); spin_lock(&inode->i_lock); inode->i_state &= ~I_SYNC; if (!(inode->i_state & I_FREEING)) { if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) { /* * We didn't write back all the pages. nfs_writepages() * sometimes bales out without doing anything. */ inode->i_state |= I_DIRTY_PAGES; if (wbc->nr_to_write <= 0) { /* * slice used up: queue for next turn */ requeue_io(inode); } else { /* * Writeback blocked by something other than * congestion. Delay the inode for some time to * avoid spinning on the CPU (100% iowait) * retrying writeback of the dirty page/inode * that cannot be performed immediately. */ redirty_tail(inode); } } else if (inode->i_state & I_DIRTY) { /* * Filesystems can dirty the inode during writeback * operations, such as delayed allocation during * submission or metadata updates after data IO * completion. */ redirty_tail(inode); } else { /* * The inode is clean. At this point we either have * a reference to the inode or it's on it's way out. * No need to add it back to the LRU. */ list_del_init(&inode->i_wb_list); } } inode_sync_complete(inode); return ret; } /* * For background writeback the caller does not have the sb pinned * before calling writeback. So make sure that we do pin it, so it doesn't * go away while we are writing inodes from it. */ static bool pin_sb_for_writeback(struct super_block *sb) { spin_lock(&sb_lock); if (list_empty(&sb->s_instances)) { spin_unlock(&sb_lock); return false; } sb->s_count++; spin_unlock(&sb_lock); if (down_read_trylock(&sb->s_umount)) { if (sb->s_root) return true; up_read(&sb->s_umount); } put_super(sb); return false; } /* * Write a portion of b_io inodes which belong to @sb. * * If @only_this_sb is true, then find and write all such * inodes. Otherwise write only ones which go sequentially * in reverse order. * * Return 1, if the caller writeback routine should be * interrupted. Otherwise return 0. */ static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb, struct writeback_control *wbc, bool only_this_sb) { while (!list_empty(&wb->b_io)) { long pages_skipped; struct inode *inode = wb_inode(wb->b_io.prev); if (inode->i_sb != sb) { if (only_this_sb) { /* * We only want to write back data for this * superblock, move all inodes not belonging * to it back onto the dirty list. */ redirty_tail(inode); continue; } /* * The inode belongs to a different superblock. * Bounce back to the caller to unpin this and * pin the next superblock. */ return 0; } /* * Don't bother with new inodes or inodes beeing freed, first * kind does not need peridic writeout yet, and for the latter * kind writeout is handled by the freer. */ spin_lock(&inode->i_lock); if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) { spin_unlock(&inode->i_lock); requeue_io(inode); continue; } /* * Was this inode dirtied after sync_sb_inodes was called? * This keeps sync from extra jobs and livelock. */ if (inode_dirtied_after(inode, wbc->wb_start)) { spin_unlock(&inode->i_lock); return 1; } __iget(inode); pages_skipped = wbc->pages_skipped; writeback_single_inode(inode, wbc); if (wbc->pages_skipped != pages_skipped) { /* * writeback is not making progress due to locked * buffers. Skip this inode for now. */ redirty_tail(inode); } spin_unlock(&inode->i_lock); spin_unlock(&inode_wb_list_lock); iput(inode); cond_resched(); spin_lock(&inode_wb_list_lock); if (wbc->nr_to_write <= 0) { wbc->more_io = 1; return 1; } if (!list_empty(&wb->b_more_io)) wbc->more_io = 1; } /* b_io is empty */ return 1; } void writeback_inodes_wb(struct bdi_writeback *wb, struct writeback_control *wbc) { int ret = 0; if (!wbc->wb_start) wbc->wb_start = jiffies; /* livelock avoidance */ spin_lock(&inode_wb_list_lock); if (!wbc->for_kupdate || list_empty(&wb->b_io)) queue_io(wb, wbc->older_than_this); while (!list_empty(&wb->b_io)) { struct inode *inode = wb_inode(wb->b_io.prev); struct super_block *sb = inode->i_sb; if (!pin_sb_for_writeback(sb)) { requeue_io(inode); continue; } ret = writeback_sb_inodes(sb, wb, wbc, false); drop_super(sb); if (ret) break; } spin_unlock(&inode_wb_list_lock); /* Leave any unwritten inodes on b_io */ } static void __writeback_inodes_sb(struct super_block *sb, struct bdi_writeback *wb, struct writeback_control *wbc) { WARN_ON(!rwsem_is_locked(&sb->s_umount)); spin_lock(&inode_wb_list_lock); if (!wbc->for_kupdate || list_empty(&wb->b_io)) queue_io(wb, wbc->older_than_this); writeback_sb_inodes(sb, wb, wbc, true); spin_unlock(&inode_wb_list_lock); } /* * The maximum number of pages to writeout in a single bdi flush/kupdate * operation. We do this so we don't hold I_SYNC against an inode for * enormous amounts of time, which would block a userspace task which has * been forced to throttle against that inode. Also, the code reevaluates * the dirty each time it has written this many pages. */ #define MAX_WRITEBACK_PAGES 1024 static inline bool over_bground_thresh(void) { unsigned long background_thresh, dirty_thresh; global_dirty_limits(&background_thresh, &dirty_thresh); return (global_page_state(NR_FILE_DIRTY) + global_page_state(NR_UNSTABLE_NFS) > background_thresh); } /* * Explicit flushing or periodic writeback of "old" data. * * Define "old": the first time one of an inode's pages is dirtied, we mark the * dirtying-time in the inode's address_space. So this periodic writeback code * just walks the superblock inode list, writing back any inodes which are * older than a specific point in time. * * Try to run once per dirty_writeback_interval. But if a writeback event * takes longer than a dirty_writeback_interval interval, then leave a * one-second gap. * * older_than_this takes precedence over nr_to_write. So we'll only write back * all dirty pages if they are all attached to "old" mappings. */ static long wb_writeback(struct bdi_writeback *wb, struct wb_writeback_work *work) { struct writeback_control wbc = { .sync_mode = work->sync_mode, .older_than_this = NULL, .for_kupdate = work->for_kupdate, .for_background = work->for_background, .range_cyclic = work->range_cyclic, }; unsigned long oldest_jif; long wrote = 0; long write_chunk; struct inode *inode; if (wbc.for_kupdate) { wbc.older_than_this = &oldest_jif; oldest_jif = jiffies - msecs_to_jiffies(dirty_expire_interval * 10); } if (!wbc.range_cyclic) { wbc.range_start = 0; wbc.range_end = LLONG_MAX; } /* * WB_SYNC_ALL mode does livelock avoidance by syncing dirty * inodes/pages in one big loop. Setting wbc.nr_to_write=LONG_MAX * here avoids calling into writeback_inodes_wb() more than once. * * The intended call sequence for WB_SYNC_ALL writeback is: * * wb_writeback() * __writeback_inodes_sb() <== called only once * write_cache_pages() <== called once for each inode * (quickly) tag currently dirty pages * (maybe slowly) sync all tagged pages */ if (wbc.sync_mode == WB_SYNC_NONE) write_chunk = MAX_WRITEBACK_PAGES; else write_chunk = LONG_MAX; wbc.wb_start = jiffies; /* livelock avoidance */ for (;;) { /* * Stop writeback when nr_pages has been consumed */ if (work->nr_pages <= 0) break; /* * Background writeout and kupdate-style writeback may * run forever. Stop them if there is other work to do * so that e.g. sync can proceed. They'll be restarted * after the other works are all done. */ if ((work->for_background || work->for_kupdate) && !list_empty(&wb->bdi->work_list)) break; /* * For background writeout, stop when we are below the * background dirty threshold */ if (work->for_background && !over_bground_thresh()) break; wbc.more_io = 0; wbc.nr_to_write = write_chunk; wbc.pages_skipped = 0; trace_wbc_writeback_start(&wbc, wb->bdi); if (work->sb) __writeback_inodes_sb(work->sb, wb, &wbc); else writeback_inodes_wb(wb, &wbc); trace_wbc_writeback_written(&wbc, wb->bdi); work->nr_pages -= write_chunk - wbc.nr_to_write; wrote += write_chunk - wbc.nr_to_write; /* * If we consumed everything, see if we have more */ if (wbc.nr_to_write <= 0) continue; /* * Didn't write everything and we don't have more IO, bail */ if (!wbc.more_io) break; /* * Did we write something? Try for more */ if (wbc.nr_to_write < write_chunk) continue; /* * Nothing written. Wait for some inode to * become available for writeback. Otherwise * we'll just busyloop. */ spin_lock(&inode_wb_list_lock); if (!list_empty(&wb->b_more_io)) { inode = wb_inode(wb->b_more_io.prev); trace_wbc_writeback_wait(&wbc, wb->bdi); spin_lock(&inode->i_lock); inode_wait_for_writeback(inode); spin_unlock(&inode->i_lock); } spin_unlock(&inode_wb_list_lock); } return wrote; } /* * Return the next wb_writeback_work struct that hasn't been processed yet. */ static struct wb_writeback_work * get_next_work_item(struct backing_dev_info *bdi) { struct wb_writeback_work *work = NULL; spin_lock_bh(&bdi->wb_lock); if (!list_empty(&bdi->work_list)) { work = list_entry(bdi->work_list.next, struct wb_writeback_work, list); list_del_init(&work->list); } spin_unlock_bh(&bdi->wb_lock); return work; } /* * Add in the number of potentially dirty inodes, because each inode * write can dirty pagecache in the underlying blockdev. */ static unsigned long get_nr_dirty_pages(void) { return global_page_state(NR_FILE_DIRTY) + global_page_state(NR_UNSTABLE_NFS) + get_nr_dirty_inodes(); } static long wb_check_background_flush(struct bdi_writeback *wb) { if (over_bground_thresh()) { struct wb_writeback_work work = { .nr_pages = LONG_MAX, .sync_mode = WB_SYNC_NONE, .for_background = 1, .range_cyclic = 1, }; return wb_writeback(wb, &work); } return 0; } static long wb_check_old_data_flush(struct bdi_writeback *wb) { unsigned long expired; long nr_pages; /* * When set to zero, disable periodic writeback */ if (!dirty_writeback_interval) return 0; expired = wb->last_old_flush + msecs_to_jiffies(dirty_writeback_interval * 10); if (time_before(jiffies, expired)) return 0; wb->last_old_flush = jiffies; nr_pages = get_nr_dirty_pages(); if (nr_pages) { struct wb_writeback_work work = { .nr_pages = nr_pages, .sync_mode = WB_SYNC_NONE, .for_kupdate = 1, .range_cyclic = 1, }; return wb_writeback(wb, &work); } return 0; } /* * Retrieve work items and do the writeback they describe */ long wb_do_writeback(struct bdi_writeback *wb, int force_wait) { struct backing_dev_info *bdi = wb->bdi; struct wb_writeback_work *work; long wrote = 0; set_bit(BDI_writeback_running, &wb->bdi->state); while ((work = get_next_work_item(bdi)) != NULL) { /* * Override sync mode, in case we must wait for completion * because this thread is exiting now. */ if (force_wait) work->sync_mode = WB_SYNC_ALL; trace_writeback_exec(bdi, work); wrote += wb_writeback(wb, work); /* * Notify the caller of completion if this is a synchronous * work item, otherwise just free it. */ if (work->done) complete(work->done); else kfree(work); } /* * Check for periodic writeback, kupdated() style */ wrote += wb_check_old_data_flush(wb); wrote += wb_check_background_flush(wb); clear_bit(BDI_writeback_running, &wb->bdi->state); return wrote; } /* * Handle writeback of dirty data for the device backed by this bdi. Also * wakes up periodically and does kupdated style flushing. */ int bdi_writeback_thread(void *data) { struct bdi_writeback *wb = data; struct backing_dev_info *bdi = wb->bdi; long pages_written; current->flags |= PF_SWAPWRITE; set_freezable(); wb->last_active = jiffies; /* * Our parent may run at a different priority, just set us to normal */ set_user_nice(current, 0); trace_writeback_thread_start(bdi); while (!kthread_should_stop()) { /* * Remove own delayed wake-up timer, since we are already awake * and we'll take care of the preriodic write-back. */ del_timer(&wb->wakeup_timer); pages_written = wb_do_writeback(wb, 0); trace_writeback_pages_written(pages_written); if (pages_written) wb->last_active = jiffies; set_current_state(TASK_INTERRUPTIBLE); if (!list_empty(&bdi->work_list) || kthread_should_stop()) { __set_current_state(TASK_RUNNING); continue; } if (wb_has_dirty_io(wb) && dirty_writeback_interval) schedule_timeout(msecs_to_jiffies(dirty_writeback_interval * 10)); else { /* * We have nothing to do, so can go sleep without any * timeout and save power. When a work is queued or * something is made dirty - we will be woken up. */ schedule(); } try_to_freeze(); } /* Flush any work that raced with us exiting */ if (!list_empty(&bdi->work_list)) wb_do_writeback(wb, 1); trace_writeback_thread_stop(bdi); return 0; } /* * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back * the whole world. */ void wakeup_flusher_threads(long nr_pages) { struct backing_dev_info *bdi; if (!nr_pages) { nr_pages = global_page_state(NR_FILE_DIRTY) + global_page_state(NR_UNSTABLE_NFS); } rcu_read_lock(); list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { if (!bdi_has_dirty_io(bdi)) continue; __bdi_start_writeback(bdi, nr_pages, false); } rcu_read_unlock(); } static noinline void block_dump___mark_inode_dirty(struct inode *inode) { if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) { struct dentry *dentry; const char *name = "?"; dentry = d_find_alias(inode); if (dentry) { spin_lock(&dentry->d_lock); name = (const char *) dentry->d_name.name; } printk(KERN_DEBUG "%s(%d): dirtied inode %lu (%s) on %s\n", current->comm, task_pid_nr(current), inode->i_ino, name, inode->i_sb->s_id); if (dentry) { spin_unlock(&dentry->d_lock); dput(dentry); } } } /** * __mark_inode_dirty - internal function * @inode: inode to mark * @flags: what kind of dirty (i.e. I_DIRTY_SYNC) * Mark an inode as dirty. Callers should use mark_inode_dirty or * mark_inode_dirty_sync. * * Put the inode on the super block's dirty list. * * CAREFUL! We mark it dirty unconditionally, but move it onto the * dirty list only if it is hashed or if it refers to a blockdev. * If it was not hashed, it will never be added to the dirty list * even if it is later hashed, as it will have been marked dirty already. * * In short, make sure you hash any inodes _before_ you start marking * them dirty. * * This function *must* be atomic for the I_DIRTY_PAGES case - * set_page_dirty() is called under spinlock in several places. * * Note that for blockdevs, inode->dirtied_when represents the dirtying time of * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of * the kernel-internal blockdev inode represents the dirtying time of the * blockdev's pages. This is why for I_DIRTY_PAGES we always use * page->mapping->host, so the page-dirtying time is recorded in the internal * blockdev inode. */ void __mark_inode_dirty(struct inode *inode, int flags) { struct super_block *sb = inode->i_sb; struct backing_dev_info *bdi = NULL; /* * Don't do this for I_DIRTY_PAGES - that doesn't actually * dirty the inode itself */ if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { if (sb->s_op->dirty_inode) sb->s_op->dirty_inode(inode); } /* * make sure that changes are seen by all cpus before we test i_state * -- mikulas */ smp_mb(); /* avoid the locking if we can */ if ((inode->i_state & flags) == flags) return; if (unlikely(block_dump)) block_dump___mark_inode_dirty(inode); spin_lock(&inode->i_lock); if ((inode->i_state & flags) != flags) { const int was_dirty = inode->i_state & I_DIRTY; inode->i_state |= flags; /* * If the inode is being synced, just update its dirty state. * The unlocker will place the inode on the appropriate * superblock list, based upon its state. */ if (inode->i_state & I_SYNC) goto out_unlock_inode; /* * Only add valid (hashed) inodes to the superblock's * dirty list. Add blockdev inodes as well. */ if (!S_ISBLK(inode->i_mode)) { if (inode_unhashed(inode)) goto out_unlock_inode; } if (inode->i_state & I_FREEING) goto out_unlock_inode; /* * If the inode was already on b_dirty/b_io/b_more_io, don't * reposition it (that would break b_dirty time-ordering). */ if (!was_dirty) { bool wakeup_bdi = false; bdi = inode_to_bdi(inode); if (bdi_cap_writeback_dirty(bdi)) { WARN(!test_bit(BDI_registered, &bdi->state), "bdi-%s not registered\n", bdi->name); /* * If this is the first dirty inode for this * bdi, we have to wake-up the corresponding * bdi thread to make sure background * write-back happens later. */ if (!wb_has_dirty_io(&bdi->wb)) wakeup_bdi = true; } spin_unlock(&inode->i_lock); spin_lock(&inode_wb_list_lock); inode->dirtied_when = jiffies; list_move(&inode->i_wb_list, &bdi->wb.b_dirty); spin_unlock(&inode_wb_list_lock); if (wakeup_bdi) bdi_wakeup_thread_delayed(bdi); return; } } out_unlock_inode: spin_unlock(&inode->i_lock); } EXPORT_SYMBOL(__mark_inode_dirty); /* * Write out a superblock's list of dirty inodes. A wait will be performed * upon no inodes, all inodes or the final one, depending upon sync_mode. * * If older_than_this is non-NULL, then only write out inodes which * had their first dirtying at a time earlier than *older_than_this. * * If `bdi' is non-zero then we're being asked to writeback a specific queue. * This function assumes that the blockdev superblock's inodes are backed by * a variety of queues, so all inodes are searched. For other superblocks, * assume that all inodes are backed by the same queue. * * The inodes to be written are parked on bdi->b_io. They are moved back onto * bdi->b_dirty as they are selected for writing. This way, none can be missed * on the writer throttling path, and we get decent balancing between many * throttled threads: we don't want them all piling up on inode_sync_wait. */ static void wait_sb_inodes(struct super_block *sb) { struct inode *inode, *old_inode = NULL; /* * We need to be protected against the filesystem going from * r/o to r/w or vice versa. */ WARN_ON(!rwsem_is_locked(&sb->s_umount)); spin_lock(&inode_sb_list_lock); /* * Data integrity sync. Must wait for all pages under writeback, * because there may have been pages dirtied before our sync * call, but which had writeout started before we write it out. * In which case, the inode may not be on the dirty list, but * we still have to wait for that writeout. */ list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { struct address_space *mapping = inode->i_mapping; spin_lock(&inode->i_lock); if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) || (mapping->nrpages == 0)) { spin_unlock(&inode->i_lock); continue; } __iget(inode); spin_unlock(&inode->i_lock); spin_unlock(&inode_sb_list_lock); /* * We hold a reference to 'inode' so it couldn't have been * removed from s_inodes list while we dropped the * inode_sb_list_lock. We cannot iput the inode now as we can * be holding the last reference and we cannot iput it under * inode_sb_list_lock. So we keep the reference and iput it * later. */ iput(old_inode); old_inode = inode; filemap_fdatawait(mapping); cond_resched(); spin_lock(&inode_sb_list_lock); } spin_unlock(&inode_sb_list_lock); iput(old_inode); } /** * writeback_inodes_sb_nr - writeback dirty inodes from given super_block * @sb: the superblock * @nr: the number of pages to write * * Start writeback on some inodes on this super_block. No guarantees are made * on how many (if any) will be written, and this function does not wait * for IO completion of submitted IO. */ void writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr) { DECLARE_COMPLETION_ONSTACK(done); struct wb_writeback_work work = { .sb = sb, .sync_mode = WB_SYNC_NONE, .done = &done, .nr_pages = nr, }; WARN_ON(!rwsem_is_locked(&sb->s_umount)); bdi_queue_work(sb->s_bdi, &work); wait_for_completion(&done); } EXPORT_SYMBOL(writeback_inodes_sb_nr); /** * writeback_inodes_sb - writeback dirty inodes from given super_block * @sb: the superblock * * Start writeback on some inodes on this super_block. No guarantees are made * on how many (if any) will be written, and this function does not wait * for IO completion of submitted IO. */ void writeback_inodes_sb(struct super_block *sb) { return writeback_inodes_sb_nr(sb, get_nr_dirty_pages()); } EXPORT_SYMBOL(writeback_inodes_sb); /** * writeback_inodes_sb_if_idle - start writeback if none underway * @sb: the superblock * * Invoke writeback_inodes_sb if no writeback is currently underway. * Returns 1 if writeback was started, 0 if not. */ int writeback_inodes_sb_if_idle(struct super_block *sb) { if (!writeback_in_progress(sb->s_bdi)) { down_read(&sb->s_umount); writeback_inodes_sb(sb); up_read(&sb->s_umount); return 1; } else return 0; } EXPORT_SYMBOL(writeback_inodes_sb_if_idle); /** * writeback_inodes_sb_if_idle - start writeback if none underway * @sb: the superblock * @nr: the number of pages to write * * Invoke writeback_inodes_sb if no writeback is currently underway. * Returns 1 if writeback was started, 0 if not. */ int writeback_inodes_sb_nr_if_idle(struct super_block *sb, unsigned long nr) { if (!writeback_in_progress(sb->s_bdi)) { down_read(&sb->s_umount); writeback_inodes_sb_nr(sb, nr); up_read(&sb->s_umount); return 1; } else return 0; } EXPORT_SYMBOL(writeback_inodes_sb_nr_if_idle); /** * sync_inodes_sb - sync sb inode pages * @sb: the superblock * * This function writes and waits on any dirty inode belonging to this * super_block. */ void sync_inodes_sb(struct super_block *sb) { DECLARE_COMPLETION_ONSTACK(done); struct wb_writeback_work work = { .sb = sb, .sync_mode = WB_SYNC_ALL, .nr_pages = LONG_MAX, .range_cyclic = 0, .done = &done, }; WARN_ON(!rwsem_is_locked(&sb->s_umount)); bdi_queue_work(sb->s_bdi, &work); wait_for_completion(&done); wait_sb_inodes(sb); } EXPORT_SYMBOL(sync_inodes_sb); /** * write_inode_now - write an inode to disk * @inode: inode to write to disk * @sync: whether the write should be synchronous or not * * This function commits an inode to disk immediately if it is dirty. This is * primarily needed by knfsd. *


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