Message-Id: <1404251250-22992-25-git-send-email-tst@schoebel-theuer.de>
Date:	Tue,  1 Jul 2014 23:47:04 +0200
From:	Thomas Schoebel-Theuer <tst@...oebel-theuer.de>
To:	linux-kernel@...r.kernel.org
Subject: [PATCH 24/50] mars: add new file drivers/block/mars/xio_bricks/lib_mapfree.c

Signed-off-by: Thomas Schoebel-Theuer <tst@...oebel-theuer.de>
---
 drivers/block/mars/xio_bricks/lib_mapfree.c | 356 ++++++++++++++++++++++++++++
 1 file changed, 356 insertions(+)
 create mode 100644 drivers/block/mars/xio_bricks/lib_mapfree.c

diff --git a/drivers/block/mars/xio_bricks/lib_mapfree.c b/drivers/block/mars/xio_bricks/lib_mapfree.c
new file mode 100644
index 0000000..99a5ce9
--- /dev/null
+++ b/drivers/block/mars/xio_bricks/lib_mapfree.c
@@ -0,0 +1,356 @@
+/*  (c) 2012 Thomas Schoebel-Theuer / 1&1 Internet AG */
+
+#include <linux/lib_mapfree.h>
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/list.h>
+#include <linux/types.h>
+#include <linux/blkdev.h>
+#include <linux/spinlock.h>
+#include <linux/wait.h>
+#include <linux/file.h>
+
+/*  time to wait between background mapfree operations */
+int mapfree_period_sec = 10;
+EXPORT_SYMBOL_GPL(mapfree_period_sec);
+
+/*  some grace space where no regular cleanup should occur */
+int mapfree_grace_keep_mb = 16;
+EXPORT_SYMBOL_GPL(mapfree_grace_keep_mb);
+
+static
+DECLARE_RWSEM(mapfree_mutex);
+
+static
+LIST_HEAD(mapfree_list);
+
+static
+void mapfree_pages(struct mapfree_info *mf, int grace_keep)
+{
+	struct address_space *mapping;
+	pgoff_t start;
+	pgoff_t end;
+
+	if (unlikely(!mf->mf_filp))
+		goto done;
+
+	mapping = mf->mf_filp->f_mapping;
+	if (unlikely(!mapping))
+		goto done;
+
+	if (grace_keep < 0) { /*  force full flush */
+		start = 0;
+		end = -1;
+	} else {
+		loff_t tmp;
+		loff_t min;
+
+		spin_lock(&mf->mf_lock);
+
+		min = tmp = mf->mf_min[0];
+		if (likely(mf->mf_min[1] < min))
+			min = mf->mf_min[1];
+		if (tmp) {
+			mf->mf_min[1] = tmp;
+			mf->mf_min[0] = 0;
+		}
+
+		spin_unlock(&mf->mf_lock);
+
+		min -= (loff_t)grace_keep * (1024 * 1024); /*  megabytes */
+		end = 0;
+
+		if (min > 0 || mf->mf_last) {
+			start = mf->mf_last / PAGE_SIZE;
+			/*  add some grace overlapping */
+			if (likely(start > 0))
+				start--;
+			mf->mf_last = min;
+			end = min / PAGE_SIZE;
+		} else	{ /*  there was no progress for at least 2 rounds */
+			start = 0;
+			if (!grace_keep) /*  also flush thoroughly */
+				end = -1;
+		}
+
+		XIO_DBG("file = '%s' start = %lu end = %lu\n", SAFE_STR(mf->mf_name), start, end);
+	}
+
+	if (end > start || end == -1)
+		invalidate_mapping_pages(mapping, start, end);
+
+done:;
+}
+
+static
+void _mapfree_put(struct mapfree_info *mf)
+{
+	if (atomic_dec_and_test(&mf->mf_count)) {
+		XIO_DBG("closing file '%s' filp = %p\n", mf->mf_name, mf->mf_filp);
+		list_del_init(&mf->mf_head);
+		CHECK_HEAD_EMPTY(&mf->mf_dirty_anchor);
+		if (likely(mf->mf_filp)) {
+			mapfree_pages(mf, -1);
+			filp_close(mf->mf_filp, NULL);
+		}
+		brick_string_free(mf->mf_name);
+		brick_mem_free(mf);
+	}
+}
+
+void mapfree_put(struct mapfree_info *mf)
+{
+	down_write(&mapfree_mutex);
+	_mapfree_put(mf);
+	up_write(&mapfree_mutex);
+}
+EXPORT_SYMBOL_GPL(mapfree_put);
+
+struct mapfree_info *mapfree_get(const char *name, int flags)
+{
+	struct mapfree_info *mf = NULL;
+	struct list_head *tmp;
+
+	if (!(flags & O_DIRECT)) {
+		down_read(&mapfree_mutex);
+		for (tmp = mapfree_list.next; tmp != &mapfree_list; tmp = tmp->next) {
+			struct mapfree_info *_mf = container_of(tmp, struct mapfree_info, mf_head);
+
+			if (_mf->mf_flags == flags && !strcmp(_mf->mf_name, name)) {
+				mf = _mf;
+				atomic_inc(&mf->mf_count);
+				break;
+			}
+		}
+		up_read(&mapfree_mutex);
+
+		if (mf)
+			goto done;
+	}
+
+	for (;;) {
+		struct address_space *mapping;
+		struct inode *inode = NULL;
+		int ra = 1;
+		int prot = 0600;
+
+		mm_segment_t oldfs;
+
+		mf = brick_zmem_alloc(sizeof(struct mapfree_info));
+
+		mf->mf_name = brick_strdup(name);
+
+		mf->mf_flags = flags;
+		INIT_LIST_HEAD(&mf->mf_head);
+		INIT_LIST_HEAD(&mf->mf_dirty_anchor);
+		atomic_set(&mf->mf_count, 1);
+		spin_lock_init(&mf->mf_lock);
+		mf->mf_max = -1;
+
+		oldfs = get_fs();
+		set_fs(get_ds());
+		mf->mf_filp = filp_open(name, flags, prot);
+		set_fs(oldfs);
+
+		XIO_DBG("file '%s' flags = %d prot = %d filp = %p\n", name, flags, prot, mf->mf_filp);
+
+		if (unlikely(!mf->mf_filp || IS_ERR(mf->mf_filp))) {
+			int err = PTR_ERR(mf->mf_filp);
+
+			XIO_ERR("can't open file '%s' status=%d\n", name, err);
+			mf->mf_filp = NULL;
+			_mapfree_put(mf);
+			mf = NULL;
+			break;
+		}
+
+		mapping = mf->mf_filp->f_mapping;
+		if (likely(mapping))
+			inode = mapping->host;
+		if (unlikely(!mapping || !inode)) {
+			XIO_ERR("file '%s' has no mapping\n", name);
+			mf->mf_filp = NULL;
+			_mapfree_put(mf);
+			mf = NULL;
+			break;
+		}
+
+		mapping_set_gfp_mask(mapping, mapping_gfp_mask(mapping) & ~(__GFP_IO | __GFP_FS));
+
+		mf->mf_max = i_size_read(inode);
+
+		if (S_ISBLK(inode->i_mode)) {
+			XIO_INF("changing blkdev readahead from %lu to %d\n",
+				inode->i_bdev->bd_disk->queue->backing_dev_info.ra_pages,
+				ra);
+			inode->i_bdev->bd_disk->queue->backing_dev_info.ra_pages = ra;
+		}
+
+		if (flags & O_DIRECT) { /*  never share them */
+			break;
+		}
+
+		/*  maintain global list of all open files */
+		down_write(&mapfree_mutex);
+		for (tmp = mapfree_list.next; tmp != &mapfree_list; tmp = tmp->next) {
+			struct mapfree_info *_mf = container_of(tmp, struct mapfree_info, mf_head);
+
+			if (unlikely(_mf->mf_flags == flags && !strcmp(_mf->mf_name, name))) {
+				XIO_WRN("race on creation of '%s' detected\n", name);
+				_mapfree_put(mf);
+				mf = _mf;
+				atomic_inc(&mf->mf_count);
+				goto leave;
+			}
+		}
+		list_add_tail(&mf->mf_head, &mapfree_list);
+leave:
+		up_write(&mapfree_mutex);
+		break;
+	}
+done:
+	return mf;
+}
+EXPORT_SYMBOL_GPL(mapfree_get);
+
+void mapfree_set(struct mapfree_info *mf, loff_t min, loff_t max)
+{
+	spin_lock(&mf->mf_lock);
+	if (!mf->mf_min[0] || mf->mf_min[0] > min)
+		mf->mf_min[0] = min;
+	if (max >= 0 && mf->mf_max < max)
+		mf->mf_max = max;
+	spin_unlock(&mf->mf_lock);
+}
+EXPORT_SYMBOL_GPL(mapfree_set);
+
+static
+int mapfree_thread(void *data)
+{
+	while (!brick_thread_should_stop()) {
+		struct mapfree_info *mf = NULL;
+		struct list_head *tmp;
+		long long eldest = 0;
+
+		brick_msleep(500);
+
+		if (mapfree_period_sec <= 0)
+			continue;
+
+		down_read(&mapfree_mutex);
+
+		for (tmp = mapfree_list.next; tmp != &mapfree_list; tmp = tmp->next) {
+			struct mapfree_info *_mf = container_of(tmp, struct mapfree_info, mf_head);
+
+			if (unlikely(!_mf->mf_jiffies)) {
+				_mf->mf_jiffies = jiffies;
+				continue;
+			}
+			if ((long long)jiffies - _mf->mf_jiffies > mapfree_period_sec * HZ &&
+			    (!mf || _mf->mf_jiffies < eldest)) {
+				mf = _mf;
+				eldest = _mf->mf_jiffies;
+			}
+		}
+		if (mf)
+			atomic_inc(&mf->mf_count);
+
+		up_read(&mapfree_mutex);
+
+		if (!mf)
+			continue;
+
+		mapfree_pages(mf, mapfree_grace_keep_mb);
+
+		mf->mf_jiffies = jiffies;
+		mapfree_put(mf);
+	}
+	return 0;
+}
+
+/***************** dirty IOs on the fly  *****************/
+
+void mf_insert_dirty(struct mapfree_info *mf, struct dirty_info *di)
+{
+	if (likely(di->dirty_aio)) {
+		spin_lock(&mf->mf_lock);
+		list_del(&di->dirty_head);
+		list_add(&di->dirty_head, &mf->mf_dirty_anchor);
+		spin_unlock(&mf->mf_lock);
+	}
+}
+EXPORT_SYMBOL_GPL(mf_insert_dirty);
+
+void mf_remove_dirty(struct mapfree_info *mf, struct dirty_info *di)
+{
+	if (!list_empty(&di->dirty_head)) {
+		spin_lock(&mf->mf_lock);
+		list_del_init(&di->dirty_head);
+		spin_unlock(&mf->mf_lock);
+	}
+}
+EXPORT_SYMBOL_GPL(mf_remove_dirty);
+
+void mf_get_dirty(struct mapfree_info *mf, loff_t *min, loff_t *max, int min_stage, int max_stage)
+{
+	struct list_head *tmp;
+
+	spin_lock(&mf->mf_lock);
+	for (tmp = mf->mf_dirty_anchor.next; tmp != &mf->mf_dirty_anchor; tmp = tmp->next) {
+		struct dirty_info *di = container_of(tmp, struct dirty_info, dirty_head);
+		struct aio_object *aio = di->dirty_aio;
+
+		if (unlikely(!aio))
+			continue;
+		if (di->dirty_stage < min_stage || di->dirty_stage > max_stage)
+			continue;
+		if (aio->io_pos < *min)
+			*min = aio->io_pos;
+		if (aio->io_pos + aio->io_len > *max)
+			*max = aio->io_pos + aio->io_len;
+	}
+	spin_unlock(&mf->mf_lock);
+}
+EXPORT_SYMBOL_GPL(mf_get_dirty);
+
+void mf_get_any_dirty(const char *filename, loff_t *min, loff_t *max, int min_stage, int max_stage)
+{
+	struct list_head *tmp;
+
+	down_read(&mapfree_mutex);
+	for (tmp = mapfree_list.next; tmp != &mapfree_list; tmp = tmp->next) {
+		struct mapfree_info *mf = container_of(tmp, struct mapfree_info, mf_head);
+
+		if (!strcmp(mf->mf_name, filename))
+			mf_get_dirty(mf, min, max, min_stage, max_stage);
+	}
+	up_read(&mapfree_mutex);
+}
+EXPORT_SYMBOL_GPL(mf_get_any_dirty);
+
+/***************** module init stuff ************************/
+
+static
+struct task_struct *mf_thread = NULL;
+
+int __init init_xio_mapfree(void)
+{
+	XIO_DBG("init_mapfree()\n");
+	mf_thread = brick_thread_create(mapfree_thread, NULL, "xio_mapfree");
+	if (unlikely(!mf_thread)) {
+		XIO_ERR("could not create mapfree thread\n");
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+void exit_xio_mapfree(void)
+{
+	XIO_DBG("exit_mapfree()\n");
+	if (likely(mf_thread)) {
+		brick_thread_stop(mf_thread);
+		mf_thread = NULL;
+	}
+}
-- 
2.0.0

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