/* * 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 akpm@zip.com.au * Split out of fs/inode.c * Additions for address_space-based writeback */ #include <linux/kernel.h>#include <linux/spinlock.h>#include <linux/sched.h>#include <linux/fs.h>#include <linux/mm.h>#include <linux/writeback.h>#include <linux/blkdev.h>#include <linux/backing-dev.h>#include <linux/buffer_head.h>#include "internal.h" /** * __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; /* * 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)) { struct dentry *dentry = NULL; const char *name = "?"; if (!list_empty(&inode->i_dentry)) { dentry = list_entry(inode->i_dentry.next, struct dentry, d_alias); if (dentry && dentry->d_name.name) name = (const char *) dentry->d_name.name; } if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) printk(KERN_DEBUG "%s(%d): dirtied inode %lu (%s) on %s\n", current->comm, current->pid, inode->i_ino, name, inode->i_sb->s_id); } spin_lock(&inode_lock); if ((inode->i_state & flags) != flags) { const int was_dirty = inode->i_state & I_DIRTY; inode->i_state |= flags; /* * If the inode is locked, 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_LOCK) goto out; /* * Only add valid (hashed) inodes to the superblock's * dirty list. Add blockdev inodes as well. */ if (!S_ISBLK(inode->i_mode)) { if (hlist_unhashed(&inode->i_hash)) goto out; } if (inode->i_state & (I_FREEING|I_CLEAR)) goto out; /* * If the inode was already on s_dirty or s_io, don't * reposition it (that would break s_dirty time-ordering). */ if (!was_dirty) { inode->dirtied_when = jiffies; list_move(&inode->i_list, &sb->s_dirty); } }out: spin_unlock(&inode_lock);} EXPORT_SYMBOL(__mark_inode_dirty); static int write_inode(struct inode *inode, int sync){ if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) return inode->i_sb->s_op->write_inode(inode, sync); return 0;} /* * Write a single inode's dirty pages and inode data out to disk. * 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. * * Called under inode_lock. */static int__sync_single_inode(struct inode *inode, struct writeback_control *wbc){ unsigned dirty; struct address_space *mapping = inode->i_mapping; struct super_block *sb = inode->i_sb; int wait = wbc->sync_mode == WB_SYNC_ALL; int ret; BUG_ON(inode->i_state & I_LOCK); /* Set I_LOCK, reset I_DIRTY */ dirty = inode->i_state & I_DIRTY; inode->i_state |= I_LOCK; inode->i_state &= ~I_DIRTY; spin_unlock(&inode_lock); ret = do_writepages(mapping, wbc); /* 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, wait); if (ret == 0) ret = err; } if (wait) { int err = filemap_fdatawait(mapping); if (ret == 0) ret = err; } spin_lock(&inode_lock); inode->i_state &= ~I_LOCK; if (!(inode->i_state & I_FREEING)) { if (!(inode->i_state & I_DIRTY) && mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) { /* * We didn't write back all the pages. nfs_writepages() * sometimes bales out without doing anything. Redirty * the inode. It is still on sb->s_io. */ if (wbc->for_kupdate) { /* * For the kupdate function we leave the inode * at the head of sb_dirty so it will get more * writeout as soon as the queue becomes * uncongested. */ inode->i_state |= I_DIRTY_PAGES; list_move_tail(&inode->i_list, &sb->s_dirty); } else { /* * Otherwise fully redirty the inode so that * other inodes on this superblock will get some * writeout. Otherwise heavy writing to one * file would indefinitely suspend writeout of * all the other files. */ inode->i_state |= I_DIRTY_PAGES; inode->dirtied_when = jiffies; list_move(&inode->i_list, &sb->s_dirty); } } else if (inode->i_state & I_DIRTY) { /* * Someone redirtied the inode while were writing back * the pages. */ list_move(&inode->i_list, &sb->s_dirty); } else if (atomic_read(&inode->i_count)) { /* * The inode is clean, inuse */ list_move(&inode->i_list, &inode_in_use); } else { /* * The inode is clean, unused */ list_move(&inode->i_list, &inode_unused); } } wake_up_inode(inode); return ret;} /* * Write out an inode's dirty pages. Called under inode_lock. Either the * caller has ref on the inode (either via __iget or via syscall against an fd) * or the inode has I_WILL_FREE set (via generic_forget_inode) */static int__writeback_single_inode(struct inode *inode, struct writeback_control *wbc){ wait_queue_head_t *wqh; 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 ((wbc->sync_mode != WB_SYNC_ALL) && (inode->i_state & I_LOCK)) { struct address_space *mapping = inode->i_mapping; int ret; list_move(&inode->i_list, &inode->i_sb->s_dirty); /* * Even if we don't actually write the inode itself here, * we can at least start some of the data writeout.. */ spin_unlock(&inode_lock); ret = do_writepages(mapping, wbc); spin_lock(&inode_lock); return ret; } /* * It's a data-integrity sync. We must wait. */ if (inode->i_state & I_LOCK) { DEFINE_WAIT_BIT(wq, &inode->i_state, __I_LOCK); wqh = bit_waitqueue(&inode->i_state, __I_LOCK); do { spin_unlock(&inode_lock); __wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE); spin_lock(&inode_lock); } while (inode->i_state & I_LOCK); } return __sync_single_inode(inode, wbc);} /* * 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 we're a pdlfush thread, then implement pdflush collision avoidance * against the entire list. * * WB_SYNC_HOLD is a hack for sys_sync(): reattach the inode to sb->s_dirty so * that it can be located for waiting on in __writeback_single_inode(). * * Called under inode_lock. * * 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. * * FIXME: this linear search could get expensive with many fileystems. But * how to fix? We need to go from an address_space to all inodes which share * a queue with that address_space. (Easy: have a global "dirty superblocks" * list). * * The inodes to be written are parked on sb->s_io. They are moved back onto * sb->s_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 __wait_on_inode. */static voidsync_sb_inodes(struct super_block *sb, struct writeback_control *wbc){ const unsigned long start = jiffies; /* livelock avoidance */ if (!wbc->for_kupdate || list_empty(&sb->s_io)) list_splice_init(&sb->s_dirty, &sb->s_io); while (!list_empty(&sb->s_io)) { struct inode *inode = list_entry(sb->s_io.prev, struct inode, i_list); struct address_space *mapping = inode->i_mapping; struct backing_dev_info *bdi = mapping->backing_dev_info; long pages_skipped; if (!bdi_cap_writeback_dirty(bdi)) { list_move(&inode->i_list, &sb->s_dirty); if (sb_is_blkdev_sb(sb)) { /* * Dirty memory-backed blockdev: the ramdisk * driver does this. Skip just this inode */ continue; } /* * Dirty memory-backed inode against a filesystem other * than the kernel-internal bdev filesystem. Skip the * entire superblock. */ break; } if (wbc->nonblocking && bdi_write_congested(bdi)) { wbc->encountered_congestion = 1; if (!sb_is_blkdev_sb(sb)) break; /* Skip a congested fs */ list_move(&inode->i_list, &sb->s_dirty); continue; /* Skip a congested blockdev */ } if (wbc->bdi && bdi != wbc->bdi) { if (!sb_is_blkdev_sb(sb)) break; /* fs has the wrong queue */ list_move(&inode->i_list, &sb->s_dirty); continue; /* blockdev has wrong queue */ } /* Was this inode dirtied after sync_sb_inodes was called? */ if (time_after(inode->dirtied_when, start)) break; /* Was this inode dirtied too recently? */ if (wbc->older_than_this && time_after(inode->dirtied_when, *wbc->older_than_this)) break; /* Is another pdflush already flushing this queue? */ if (current_is_pdflush() && !writeback_acquire(bdi)) break; BUG_ON(inode->i_state & I_FREEING); __iget(inode); pages_skipped = wbc->pages_skipped; __writeback_single_inode(inode, wbc); if (wbc->sync_mode == WB_SYNC_HOLD) { inode->dirtied_when = jiffies; list_move(&inode->i_list, &sb->s_dirty); } if (current_is_pdflush()) writeback_release(bdi); if (wbc->pages_skipped != pages_skipped) { /* * writeback is not making progress due to locked * buffers. Skip this inode for now. */ list_move(&inode->i_list, &sb->s_dirty); } spin_unlock(&inode_lock); iput(inode); cond_resched(); spin_lock(&inode_lock); if (wbc->nr_to_write <= 0) break; } return; /* Leave any unwritten inodes on s_io */} /* * Start writeback of dirty pagecache data against all unlocked inodes. * * Note: * We don't need to grab a reference to superblock here. If it has non-empty * ->s_dirty it's hadn't been killed yet and kill_super() won't proceed * past sync_inodes_sb() until both the ->s_dirty and ->s_io lists are * empty. Since __sync_single_inode() regains inode_lock before it finally moves * inode from superblock lists we are OK. * * If `older_than_this' is non-zero then only flush inodes which have a * flushtime older than *older_than_this. * * If `bdi' is non-zero then we will scan the first inode against each * superblock until we find the matching ones. One group will be the dirty * inodes against a filesystem. Then when we hit the dummy blockdev superblock, * sync_sb_inodes will seekout the blockdev which matches `bdi'. Maybe not * super-efficient but we're about to do a ton of I/O... */voidwriteback_inodes(struct writeback_control *wbc){ struct super_block *sb; might_sleep(); spin_lock(&sb_lock);restart: sb = sb_entry(super_blocks.prev); for (; sb != sb_entry(&super_blocks); sb = sb_entry(sb->s_list.prev)) { if (!list_empty(&sb->s_dirty) || !list_empty(&sb->s_io)) { /* we're making our own get_super here */ sb->s_count++; spin_unlock(&sb_lock); /* * If we can't get the readlock, there's no sense in * waiting around, most of the time the FS is going to * be unmounted by the time it is released. */ if (down_read_trylock(&sb->s_umount)) { if (sb->s_root) { spin_lock(&inode_lock); sync_sb_inodes(sb, wbc); spin_unlock(&inode_lock); } up_read(&sb->s_umount); } spin_lock(&sb_lock); if (__put_super_and_need_restart(sb)) goto restart; } if (wbc->nr_to_write <= 0) break; } spin_unlock(&sb_lock);} /* * writeback and wait upon the filesystem's dirty inodes. The caller will * do this in two passes - one to write, and one to wait. WB_SYNC_HOLD is * used to park the written inodes on sb->s_dirty for the wait pass. * * A finite limit is set on the number of pages which will be written. * To prevent infinite livelock of sys_sync(). * * We add in the number of potentially dirty inodes, because each inode write * can dirty pagecache in the underlying blockdev. */void sync_inodes_sb(struct super_block *sb, int wait){ struct writeback_control wbc = { .sync_mode = wait ? WB_SYNC_ALL : WB_SYNC_HOLD, .range_start = 0, .range_end = LLONG_MAX, }; unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY); unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS); wbc.nr_to_write = nr_dirty + nr_unstable + (inodes_stat.nr_inodes - inodes_stat.nr_unused) + nr_dirty + nr_unstable; wbc.nr_to_write += wbc.nr_to_write / 2; /* Bit more for luck */ spin_lock(&inode_lock); sync_sb_inodes(sb, &wbc); spin_unlock(&inode_lock);} /* * Rather lame livelock avoidance. */static void set_sb_syncing(int val){ struct super_block *sb; spin_lock(&sb_lock); sb = sb_entry(super_blocks.prev); for (; sb != sb_entry(&super_blocks); sb = sb_entry(sb->s_list.prev)) { sb->s_syncing = val; } spin_unlock(&sb_lock);Lines 1–500 of 704. Load more
/* * 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 akpm@zip.com.au * Split out of fs/inode.c * Additions for address_space-based writeback */ #include <linux/kernel.h> #include <linux/spinlock.h> #include <linux/sched.h> #include <linux/fs.h> #include <linux/mm.h> #include <linux/writeback.h> #include <linux/blkdev.h> #include <linux/backing-dev.h> #include <linux/buffer_head.h> #include "internal.h" /** * __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; /* * 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)) { struct dentry *dentry = NULL; const char *name = "?"; if (!list_empty(&inode->i_dentry)) { dentry = list_entry(inode->i_dentry.next, struct dentry, d_alias); if (dentry && dentry->d_name.name) name = (const char *) dentry->d_name.name; } if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) printk(KERN_DEBUG "%s(%d): dirtied inode %lu (%s) on %s\n", current->comm, current->pid, inode->i_ino, name, inode->i_sb->s_id); } spin_lock(&inode_lock); if ((inode->i_state & flags) != flags) { const int was_dirty = inode->i_state & I_DIRTY; inode->i_state |= flags; /* * If the inode is locked, 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_LOCK) goto out; /* * Only add valid (hashed) inodes to the superblock's * dirty list. Add blockdev inodes as well. */ if (!S_ISBLK(inode->i_mode)) { if (hlist_unhashed(&inode->i_hash)) goto out; } if (inode->i_state & (I_FREEING|I_CLEAR)) goto out; /* * If the inode was already on s_dirty or s_io, don't * reposition it (that would break s_dirty time-ordering). */ if (!was_dirty) { inode->dirtied_when = jiffies; list_move(&inode->i_list, &sb->s_dirty); } } out: spin_unlock(&inode_lock); } EXPORT_SYMBOL(__mark_inode_dirty); static int write_inode(struct inode *inode, int sync) { if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) return inode->i_sb->s_op->write_inode(inode, sync); return 0; } /* * Write a single inode's dirty pages and inode data out to disk. * 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. * * Called under inode_lock. */ static int __sync_single_inode(struct inode *inode, struct writeback_control *wbc) { unsigned dirty; struct address_space *mapping = inode->i_mapping; struct super_block *sb = inode->i_sb; int wait = wbc->sync_mode == WB_SYNC_ALL; int ret; BUG_ON(inode->i_state & I_LOCK); /* Set I_LOCK, reset I_DIRTY */ dirty = inode->i_state & I_DIRTY; inode->i_state |= I_LOCK; inode->i_state &= ~I_DIRTY; spin_unlock(&inode_lock); ret = do_writepages(mapping, wbc); /* 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, wait); if (ret == 0) ret = err; } if (wait) { int err = filemap_fdatawait(mapping); if (ret == 0) ret = err; } spin_lock(&inode_lock); inode->i_state &= ~I_LOCK; if (!(inode->i_state & I_FREEING)) { if (!(inode->i_state & I_DIRTY) && mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) { /* * We didn't write back all the pages. nfs_writepages() * sometimes bales out without doing anything. Redirty * the inode. It is still on sb->s_io. */ if (wbc->for_kupdate) { /* * For the kupdate function we leave the inode * at the head of sb_dirty so it will get more * writeout as soon as the queue becomes * uncongested. */ inode->i_state |= I_DIRTY_PAGES; list_move_tail(&inode->i_list, &sb->s_dirty); } else { /* * Otherwise fully redirty the inode so that * other inodes on this superblock will get some * writeout. Otherwise heavy writing to one * file would indefinitely suspend writeout of * all the other files. */ inode->i_state |= I_DIRTY_PAGES; inode->dirtied_when = jiffies; list_move(&inode->i_list, &sb->s_dirty); } } else if (inode->i_state & I_DIRTY) { /* * Someone redirtied the inode while were writing back * the pages. */ list_move(&inode->i_list, &sb->s_dirty); } else if (atomic_read(&inode->i_count)) { /* * The inode is clean, inuse */ list_move(&inode->i_list, &inode_in_use); } else { /* * The inode is clean, unused */ list_move(&inode->i_list, &inode_unused); } } wake_up_inode(inode); return ret; } /* * Write out an inode's dirty pages. Called under inode_lock. Either the * caller has ref on the inode (either via __iget or via syscall against an fd) * or the inode has I_WILL_FREE set (via generic_forget_inode) */ static int __writeback_single_inode(struct inode *inode, struct writeback_control *wbc) { wait_queue_head_t *wqh; 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 ((wbc->sync_mode != WB_SYNC_ALL) && (inode->i_state & I_LOCK)) { struct address_space *mapping = inode->i_mapping; int ret; list_move(&inode->i_list, &inode->i_sb->s_dirty); /* * Even if we don't actually write the inode itself here, * we can at least start some of the data writeout.. */ spin_unlock(&inode_lock); ret = do_writepages(mapping, wbc); spin_lock(&inode_lock); return ret; } /* * It's a data-integrity sync. We must wait. */ if (inode->i_state & I_LOCK) { DEFINE_WAIT_BIT(wq, &inode->i_state, __I_LOCK); wqh = bit_waitqueue(&inode->i_state, __I_LOCK); do { spin_unlock(&inode_lock); __wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE); spin_lock(&inode_lock); } while (inode->i_state & I_LOCK); } return __sync_single_inode(inode, wbc); } /* * 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 we're a pdlfush thread, then implement pdflush collision avoidance * against the entire list. * * WB_SYNC_HOLD is a hack for sys_sync(): reattach the inode to sb->s_dirty so * that it can be located for waiting on in __writeback_single_inode(). * * Called under inode_lock. * * 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. * * FIXME: this linear search could get expensive with many fileystems. But * how to fix? We need to go from an address_space to all inodes which share * a queue with that address_space. (Easy: have a global "dirty superblocks" * list). * * The inodes to be written are parked on sb->s_io. They are moved back onto * sb->s_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 __wait_on_inode. */ static void sync_sb_inodes(struct super_block *sb, struct writeback_control *wbc) { const unsigned long start = jiffies; /* livelock avoidance */ if (!wbc->for_kupdate || list_empty(&sb->s_io)) list_splice_init(&sb->s_dirty, &sb->s_io); while (!list_empty(&sb->s_io)) { struct inode *inode = list_entry(sb->s_io.prev, struct inode, i_list); struct address_space *mapping = inode->i_mapping; struct backing_dev_info *bdi = mapping->backing_dev_info; long pages_skipped; if (!bdi_cap_writeback_dirty(bdi)) { list_move(&inode->i_list, &sb->s_dirty); if (sb_is_blkdev_sb(sb)) { /* * Dirty memory-backed blockdev: the ramdisk * driver does this. Skip just this inode */ continue; } /* * Dirty memory-backed inode against a filesystem other * than the kernel-internal bdev filesystem. Skip the * entire superblock. */ break; } if (wbc->nonblocking && bdi_write_congested(bdi)) { wbc->encountered_congestion = 1; if (!sb_is_blkdev_sb(sb)) break; /* Skip a congested fs */ list_move(&inode->i_list, &sb->s_dirty); continue; /* Skip a congested blockdev */ } if (wbc->bdi && bdi != wbc->bdi) { if (!sb_is_blkdev_sb(sb)) break; /* fs has the wrong queue */ list_move(&inode->i_list, &sb->s_dirty); continue; /* blockdev has wrong queue */ } /* Was this inode dirtied after sync_sb_inodes was called? */ if (time_after(inode->dirtied_when, start)) break; /* Was this inode dirtied too recently? */ if (wbc->older_than_this && time_after(inode->dirtied_when, *wbc->older_than_this)) break; /* Is another pdflush already flushing this queue? */ if (current_is_pdflush() && !writeback_acquire(bdi)) break; BUG_ON(inode->i_state & I_FREEING); __iget(inode); pages_skipped = wbc->pages_skipped; __writeback_single_inode(inode, wbc); if (wbc->sync_mode == WB_SYNC_HOLD) { inode->dirtied_when = jiffies; list_move(&inode->i_list, &sb->s_dirty); } if (current_is_pdflush()) writeback_release(bdi); if (wbc->pages_skipped != pages_skipped) { /* * writeback is not making progress due to locked * buffers. Skip this inode for now. */ list_move(&inode->i_list, &sb->s_dirty); } spin_unlock(&inode_lock); iput(inode); cond_resched(); spin_lock(&inode_lock); if (wbc->nr_to_write <= 0) break; } return; /* Leave any unwritten inodes on s_io */ } /* * Start writeback of dirty pagecache data against all unlocked inodes. * * Note: * We don't need to grab a reference to superblock here. If it has non-empty * ->s_dirty it's hadn't been killed yet and kill_super() won't proceed * past sync_inodes_sb() until both the ->s_dirty and ->s_io lists are * empty. Since __sync_single_inode() regains inode_lock before it finally moves * inode from superblock lists we are OK. * * If `older_than_this' is non-zero then only flush inodes which have a * flushtime older than *older_than_this. * * If `bdi' is non-zero then we will scan the first inode against each * superblock until we find the matching ones. One group will be the dirty * inodes against a filesystem. Then when we hit the dummy blockdev superblock, * sync_sb_inodes will seekout the blockdev which matches `bdi'. Maybe not * super-efficient but we're about to do a ton of I/O... */ void writeback_inodes(struct writeback_control *wbc) { struct super_block *sb; might_sleep(); spin_lock(&sb_lock); restart: sb = sb_entry(super_blocks.prev); for (; sb != sb_entry(&super_blocks); sb = sb_entry(sb->s_list.prev)) { if (!list_empty(&sb->s_dirty) || !list_empty(&sb->s_io)) { /* we're making our own get_super here */ sb->s_count++; spin_unlock(&sb_lock); /* * If we can't get the readlock, there's no sense in * waiting around, most of the time the FS is going to * be unmounted by the time it is released. */ if (down_read_trylock(&sb->s_umount)) { if (sb->s_root) { spin_lock(&inode_lock); sync_sb_inodes(sb, wbc); spin_unlock(&inode_lock); } up_read(&sb->s_umount); } spin_lock(&sb_lock); if (__put_super_and_need_restart(sb)) goto restart; } if (wbc->nr_to_write <= 0) break; } spin_unlock(&sb_lock); } /* * writeback and wait upon the filesystem's dirty inodes. The caller will * do this in two passes - one to write, and one to wait. WB_SYNC_HOLD is * used to park the written inodes on sb->s_dirty for the wait pass. * * A finite limit is set on the number of pages which will be written. * To prevent infinite livelock of sys_sync(). * * We add in the number of potentially dirty inodes, because each inode write * can dirty pagecache in the underlying blockdev. */ void sync_inodes_sb(struct super_block *sb, int wait) { struct writeback_control wbc = { .sync_mode = wait ? WB_SYNC_ALL : WB_SYNC_HOLD, .range_start = 0, .range_end = LLONG_MAX, }; unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY); unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS); wbc.nr_to_write = nr_dirty + nr_unstable + (inodes_stat.nr_inodes - inodes_stat.nr_unused) + nr_dirty + nr_unstable; wbc.nr_to_write += wbc.nr_to_write / 2; /* Bit more for luck */ spin_lock(&inode_lock); sync_sb_inodes(sb, &wbc); spin_unlock(&inode_lock); } /* * Rather lame livelock avoidance. */ static void set_sb_syncing(int val) { struct super_block *sb; spin_lock(&sb_lock); sb = sb_entry(super_blocks.prev); for (; sb != sb_entry(&super_blocks); sb = sb_entry(sb->s_list.prev)) { sb->s_syncing = val; } spin_unlock(&sb_lock);