pnfs/blocklayout: rewrite extent tracking

Currently the block layout driver tracks extents in three separate
data structures:

 - the two list of pnfs_block_extent structures returned by the server
 - the list of sectors that were in invalid state but have been written to
 - a list of pnfs_block_short_extent structures for LAYOUTCOMMIT

All of these share the property that they are not only highly inefficient
data structures, but also that operations on them are even more inefficient
than nessecary.

In addition there are various implementation defects like:

 - using an int to track sectors, causing corruption for large offsets
 - incorrect normalization of page or block granularity ranges
 - insufficient error handling
 - incorrect synchronization as extents can be modified while they are in
   use

This patch replace all three data with a single unified rbtree structure
tracking all extents, as well as their in-memory state, although we still
need to instance for read-only and read-write extent due to the arcane
client side COW feature in the block layouts spec.

To fix the problem of extent possibly being modified while in use we make
sure to return a copy of the extent for use in the write path - the
extent can only be invalidated by a layout recall or return which has
to wait until the I/O operations finished due to refcounts on the layout
segment.

The new extent tree work similar to the schemes used by block based
filesystems like XFS or ext4.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

1 files changed, 66 insertions, 192 deletions

diff --git a/fs/nfs/blocklayout/blocklayout.c b/fs/nfs/blocklayout/blocklayout.c
index 5aa23750a14..8502e620f64 100644
--- a/fs/nfs/blocklayout/blocklayout.c
+++ b/fs/nfs/blocklayout/blocklayout.c
@@ -49,26 +49,16 @@ MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Andy Adamson <andros@citi.umich.edu>");
 MODULE_DESCRIPTION("The NFSv4.1 pNFS Block layout driver");
 
-/* Given the be associated with isect, determine if page data needs to be
- * initialized.
- */
-static int is_hole(struct pnfs_block_extent *be, sector_t isect)
-{
-	if (be->be_state == PNFS_BLOCK_NONE_DATA)
-		return 1;
-	else if (be->be_state != PNFS_BLOCK_INVALID_DATA)
-		return 0;
-	else
-		return !bl_is_sector_init(be->be_inval, isect);
-}
-
-/* Given the be associated with isect, determine if page data can be
- * written to disk.
- */
-static int is_writable(struct pnfs_block_extent *be, sector_t isect)
+static bool is_hole(struct pnfs_block_extent *be)
 {
-	return (be->be_state == PNFS_BLOCK_READWRITE_DATA ||
-		be->be_state == PNFS_BLOCK_INVALID_DATA);
+	switch (be->be_state) {
+	case PNFS_BLOCK_NONE_DATA:
+		return true;
+	case PNFS_BLOCK_INVALID_DATA:
+		return be->be_tag ? false : true;
+	default:
+		return false;
+	}
 }
 
 /* The data we are handed might be spread across several bios.  We need
@@ -76,9 +66,8 @@ static int is_writable(struct pnfs_block_extent *be, sector_t isect)
  */
 struct parallel_io {
 	struct kref refcnt;
-	void (*pnfs_callback) (void *data, int num_se);
+	void (*pnfs_callback) (void *data);
 	void *data;
-	int bse_count;
 };
 
 static inline struct parallel_io *alloc_parallel(void *data)
@@ -89,7 +78,6 @@ static inline struct parallel_io *alloc_parallel(void *data)
 	if (rv) {
 		rv->data = data;
 		kref_init(&rv->refcnt);
-		rv->bse_count = 0;
 	}
 	return rv;
 }
@@ -104,7 +92,7 @@ static void destroy_parallel(struct kref *kref)
 	struct parallel_io *p = container_of(kref, struct parallel_io, refcnt);
 
 	dprintk("%s enter\n", __func__);
-	p->pnfs_callback(p->data, p->bse_count);
+	p->pnfs_callback(p->data);
 	kfree(p);
 }
 
@@ -200,7 +188,7 @@ static void bl_read_cleanup(struct work_struct *work)
 }
 
 static void
-bl_end_par_io_read(void *data, int unused)
+bl_end_par_io_read(void *data)
 {
 	struct nfs_pgio_header *hdr = data;
 
@@ -210,56 +198,46 @@ bl_end_par_io_read(void *data, int unused)
 }
 
 static enum pnfs_try_status
-bl_read_pagelist(struct nfs_pgio_header *hdr)
+bl_read_pagelist(struct nfs_pgio_header *header)
 {
-	struct nfs_pgio_header *header = hdr;
-	int i, hole;
+	struct pnfs_block_layout *bl = BLK_LSEG2EXT(header->lseg);
 	struct bio *bio = NULL;
-	struct pnfs_block_extent *be = NULL, *cow_read = NULL;
+	struct pnfs_block_extent be;
 	sector_t isect, extent_length = 0;
 	struct parallel_io *par;
-	loff_t f_offset = hdr->args.offset;
-	size_t bytes_left = hdr->args.count;
+	loff_t f_offset = header->args.offset;
+	size_t bytes_left = header->args.count;
 	unsigned int pg_offset, pg_len;
-	struct page **pages = hdr->args.pages;
-	int pg_index = hdr->args.pgbase >> PAGE_CACHE_SHIFT;
+	struct page **pages = header->args.pages;
+	int pg_index = header->args.pgbase >> PAGE_CACHE_SHIFT;
 	const bool is_dio = (header->dreq != NULL);
 	struct blk_plug plug;
+	int i;
 
 	dprintk("%s enter nr_pages %u offset %lld count %u\n", __func__,
-		hdr->page_array.npages, f_offset,
-		(unsigned int)hdr->args.count);
+		header->page_array.npages, f_offset,
+		(unsigned int)header->args.count);
 
-	par = alloc_parallel(hdr);
+	par = alloc_parallel(header);
 	if (!par)
-		goto use_mds;
+		return PNFS_NOT_ATTEMPTED;
 	par->pnfs_callback = bl_end_par_io_read;
-	/* At this point, we can no longer jump to use_mds */
 
 	blk_start_plug(&plug);
 
 	isect = (sector_t) (f_offset >> SECTOR_SHIFT);
 	/* Code assumes extents are page-aligned */
-	for (i = pg_index; i < hdr->page_array.npages; i++) {
+	for (i = pg_index; i < header->page_array.npages; i++) {
 		if (extent_length <= 0) {
 			/* We've used up the previous extent */
-			bl_put_extent(be);
-			bl_put_extent(cow_read);
 			bio = bl_submit_bio(READ, bio);
+
 			/* Get the next one */
-			be = bl_find_get_extent(BLK_LSEG2EXT(header->lseg),
-					     isect, &cow_read);
-			if (!be) {
+			if (!ext_tree_lookup(bl, isect, &be, false)) {
 				header->pnfs_error = -EIO;
 				goto out;
 			}
-			extent_length = be->be_length -
-				(isect - be->be_f_offset);
-			if (cow_read) {
-				sector_t cow_length = cow_read->be_length -
-					(isect - cow_read->be_f_offset);
-				extent_length = min(extent_length, cow_length);
-			}
+			extent_length = be.be_length - (isect - be.be_f_offset);
 		}
 
 		pg_offset = f_offset & ~PAGE_CACHE_MASK;
@@ -278,20 +256,16 @@ bl_read_pagelist(struct nfs_pgio_header *hdr)
 			pg_len = PAGE_CACHE_SIZE;
 		}
 
-		hole = is_hole(be, isect);
-		if (hole && !cow_read) {
+		if (is_hole(&be)) {
 			bio = bl_submit_bio(READ, bio);
 			/* Fill hole w/ zeroes w/o accessing device */
 			dprintk("%s Zeroing page for hole\n", __func__);
 			zero_user_segment(pages[i], pg_offset, pg_len);
 		} else {
-			struct pnfs_block_extent *be_read;
-
-			be_read = (hole && cow_read) ? cow_read : be;
 			bio = do_add_page_to_bio(bio,
-						 hdr->page_array.npages - i,
+						 header->page_array.npages - i,
 						 READ,
-						 isect, pages[i], be_read,
+						 isect, pages[i], &be,
 						 bl_end_io_read, par,
 						 pg_offset, pg_len);
 			if (IS_ERR(bio)) {
@@ -304,50 +278,16 @@ bl_read_pagelist(struct nfs_pgio_header *hdr)
 		extent_length -= (pg_len >> SECTOR_SHIFT);
 	}
 	if ((isect << SECTOR_SHIFT) >= header->inode->i_size) {
-		hdr->res.eof = 1;
-		hdr->res.count = header->inode->i_size - hdr->args.offset;
+		header->res.eof = 1;
+		header->res.count = header->inode->i_size - header->args.offset;
 	} else {
-		hdr->res.count = (isect << SECTOR_SHIFT) - hdr->args.offset;
+		header->res.count = (isect << SECTOR_SHIFT) - header->args.offset;
 	}
 out:
-	bl_put_extent(be);
-	bl_put_extent(cow_read);
 	bl_submit_bio(READ, bio);
 	blk_finish_plug(&plug);
 	put_parallel(par);
 	return PNFS_ATTEMPTED;
-
- use_mds:
-	dprintk("Giving up and using normal NFS\n");
-	return PNFS_NOT_ATTEMPTED;
-}
-
-static void mark_extents_written(struct pnfs_block_layout *bl,
-				 __u64 offset, __u32 count)
-{
-	sector_t isect, end;
-	struct pnfs_block_extent *be;
-	struct pnfs_block_short_extent *se;
-
-	dprintk("%s(%llu, %u)\n", __func__, offset, count);
-	if (count == 0)
-		return;
-	isect = (offset & (long)(PAGE_CACHE_MASK)) >> SECTOR_SHIFT;
-	end = (offset + count + PAGE_CACHE_SIZE - 1) & (long)(PAGE_CACHE_MASK);
-	end >>= SECTOR_SHIFT;
-	while (isect < end) {
-		sector_t len;
-		be = bl_find_get_extent(bl, isect, NULL);
-		BUG_ON(!be); /* FIXME */
-		len = min(end, be->be_f_offset + be->be_length) - isect;
-		if (be->be_state == PNFS_BLOCK_INVALID_DATA) {
-			se = bl_pop_one_short_extent(be->be_inval);
-			BUG_ON(!se);
-			bl_mark_for_commit(be, isect, len, se);
-		}
-		isect += len;
-		bl_put_extent(be);
-	}
 }
 
 static void bl_end_io_write(struct bio *bio, int err)
@@ -370,29 +310,30 @@ static void bl_end_io_write(struct bio *bio, int err)
  */
 static void bl_write_cleanup(struct work_struct *work)
 {
-	struct rpc_task *task;
-	struct nfs_pgio_header *hdr;
+	struct rpc_task *task = container_of(work, struct rpc_task, u.tk_work);
+	struct nfs_pgio_header *hdr =
+			container_of(task, struct nfs_pgio_header, task);
+
 	dprintk("%s enter\n", __func__);
-	task = container_of(work, struct rpc_task, u.tk_work);
-	hdr = container_of(task, struct nfs_pgio_header, task);
+
 	if (likely(!hdr->pnfs_error)) {
-		/* Marks for LAYOUTCOMMIT */
-		mark_extents_written(BLK_LSEG2EXT(hdr->lseg),
-				     hdr->args.offset, hdr->args.count);
+		struct pnfs_block_layout *bl = BLK_LSEG2EXT(hdr->lseg);
+		u64 start = hdr->args.offset & (loff_t)PAGE_CACHE_MASK;
+		u64 end = (hdr->args.offset + hdr->args.count +
+			PAGE_CACHE_SIZE - 1) & (loff_t)PAGE_CACHE_MASK;
+
+		ext_tree_mark_written(bl, start >> SECTOR_SHIFT,
+					(end - start) >> SECTOR_SHIFT);
 	}
+
 	pnfs_ld_write_done(hdr);
 }
 
 /* Called when last of bios associated with a bl_write_pagelist call finishes */
-static void bl_end_par_io_write(void *data, int num_se)
+static void bl_end_par_io_write(void *data)
 {
 	struct nfs_pgio_header *hdr = data;
 
-	if (unlikely(hdr->pnfs_error)) {
-		bl_free_short_extents(&BLK_LSEG2EXT(hdr->lseg)->bl_inval,
-					num_se);
-	}
-
 	hdr->task.tk_status = hdr->pnfs_error;
 	hdr->verf.committed = NFS_FILE_SYNC;
 	INIT_WORK(&hdr->task.u.tk_work, bl_write_cleanup);
@@ -402,9 +343,9 @@ static void bl_end_par_io_write(void *data, int num_se)
 static enum pnfs_try_status
 bl_write_pagelist(struct nfs_pgio_header *header, int sync)
 {
-	int i, ret;
+	struct pnfs_block_layout *bl = BLK_LSEG2EXT(header->lseg);
 	struct bio *bio = NULL;
-	struct pnfs_block_extent *be = NULL;
+	struct pnfs_block_extent be;
 	sector_t isect, extent_length = 0;
 	struct parallel_io *par = NULL;
 	loff_t offset = header->args.offset;
@@ -412,6 +353,7 @@ bl_write_pagelist(struct nfs_pgio_header *header, int sync)
 	struct page **pages = header->args.pages;
 	int pg_index = pg_index = header->args.pgbase >> PAGE_CACHE_SHIFT;
 	struct blk_plug plug;
+	int i;
 
 	dprintk("%s enter, %Zu@%lld\n", __func__, count, offset);
 
@@ -421,9 +363,8 @@ bl_write_pagelist(struct nfs_pgio_header *header, int sync)
 	 */
 	par = alloc_parallel(header);
 	if (!par)
-		goto out_mds;
+		return PNFS_NOT_ATTEMPTED;
 	par->pnfs_callback = bl_end_par_io_write;
-	/* At this point, have to be more careful with error handling */
 
 	blk_start_plug(&plug);
 
@@ -434,44 +375,18 @@ bl_write_pagelist(struct nfs_pgio_header *header, int sync)
 	for (i = pg_index; i < header->page_array.npages; i++) {
 		if (extent_length <= 0) {
 			/* We've used up the previous extent */
-			bl_put_extent(be);
 			bio = bl_submit_bio(WRITE, bio);
 			/* Get the next one */
-			be = bl_find_get_extent(BLK_LSEG2EXT(header->lseg),
-					     isect, NULL);
-			if (!be || !is_writable(be, isect)) {
+			if (!ext_tree_lookup(bl, isect, &be, true)) {
 				header->pnfs_error = -EINVAL;
 				goto out;
 			}
-			if (be->be_state == PNFS_BLOCK_INVALID_DATA) {
-				if (likely(!bl_push_one_short_extent(
-								be->be_inval)))
-					par->bse_count++;
-				else {
-					header->pnfs_error = -ENOMEM;
-					goto out;
-				}
-			}
-			extent_length = be->be_length -
-			    (isect - be->be_f_offset);
-		}
 
-		BUG_ON(offset & ~PAGE_CACHE_MASK);
-
-		if (be->be_state == PNFS_BLOCK_INVALID_DATA &&
-		    !bl_is_sector_init(be->be_inval, isect)) {
-			ret = bl_mark_sectors_init(be->be_inval, isect,
-						       PAGE_CACHE_SECTORS);
-			if (unlikely(ret)) {
-				dprintk("%s bl_mark_sectors_init fail %d\n",
-					__func__, ret);
-				header->pnfs_error = ret;
-				goto out;
-			}
+			extent_length = be.be_length - (isect - be.be_f_offset);
 		}
 
 		bio = do_add_page_to_bio(bio, header->page_array.npages - i,
-					 WRITE, isect, pages[i], be,
+					 WRITE, isect, pages[i], &be,
 					 bl_end_io_write, par,
 					 0, PAGE_CACHE_SIZE);
 		if (IS_ERR(bio)) {
@@ -487,60 +402,22 @@ bl_write_pagelist(struct nfs_pgio_header *header, int sync)
 
 	header->res.count = header->args.count;
 out:
-	bl_put_extent(be);
 	bl_submit_bio(WRITE, bio);
 	blk_finish_plug(&plug);
 	put_parallel(par);
 	return PNFS_ATTEMPTED;
-out_mds:
-	return PNFS_NOT_ATTEMPTED;
-}
-
-/* FIXME - range ignored */
-static void
-release_extents(struct pnfs_block_layout *bl, struct pnfs_layout_range *range)
-{
-	int i;
-	struct pnfs_block_extent *be;
-
-	spin_lock(&bl->bl_ext_lock);
-	for (i = 0; i < EXTENT_LISTS; i++) {
-		while (!list_empty(&bl->bl_extents[i])) {
-			be = list_first_entry(&bl->bl_extents[i],
-					      struct pnfs_block_extent,
-					      be_node);
-			list_del(&be->be_node);
-			bl_put_extent(be);
-		}
-	}
-	spin_unlock(&bl->bl_ext_lock);
-}
-
-static void
-release_inval_marks(struct pnfs_inval_markings *marks)
-{
-	struct pnfs_inval_tracking *pos, *temp;
-	struct pnfs_block_short_extent *se, *stemp;
-
-	list_for_each_entry_safe(pos, temp, &marks->im_tree.mtt_stub, it_link) {
-		list_del(&pos->it_link);
-		kfree(pos);
-	}
-
-	list_for_each_entry_safe(se, stemp, &marks->im_extents, bse_node) {
-		list_del(&se->bse_node);
-		kfree(se);
-	}
-	return;
 }
 
 static void bl_free_layout_hdr(struct pnfs_layout_hdr *lo)
 {
 	struct pnfs_block_layout *bl = BLK_LO2EXT(lo);
+	int err;
 
 	dprintk("%s enter\n", __func__);
-	release_extents(bl, NULL);
-	release_inval_marks(&bl->bl_inval);
+
+	err = ext_tree_remove(bl, true, 0, LLONG_MAX);
+	WARN_ON(err);
+
 	kfree(bl);
 }
 
@@ -553,14 +430,11 @@ static struct pnfs_layout_hdr *bl_alloc_layout_hdr(struct inode *inode,
 	bl = kzalloc(sizeof(*bl), gfp_flags);
 	if (!bl)
 		return NULL;
+
+	bl->bl_ext_rw = RB_ROOT;
+	bl->bl_ext_ro = RB_ROOT;
 	spin_lock_init(&bl->bl_ext_lock);
-	INIT_LIST_HEAD(&bl->bl_extents[0]);
-	INIT_LIST_HEAD(&bl->bl_extents[1]);
-	INIT_LIST_HEAD(&bl->bl_commit);
-	INIT_LIST_HEAD(&bl->bl_committing);
-	bl->bl_count = 0;
-	bl->bl_blocksize = NFS_SERVER(inode)->pnfs_blksize >> SECTOR_SHIFT;
-	BL_INIT_INVAL_MARKS(&bl->bl_inval, bl->bl_blocksize);
+
 	return &bl->bl_layout;
 }
 
@@ -600,7 +474,7 @@ bl_encode_layoutcommit(struct pnfs_layout_hdr *lo, struct xdr_stream *xdr,
 		       const struct nfs4_layoutcommit_args *arg)
 {
 	dprintk("%s enter\n", __func__);
-	encode_pnfs_block_layoutupdate(BLK_LO2EXT(lo), xdr, arg);
+	ext_tree_encode_commit(BLK_LO2EXT(lo), xdr);
 }
 
 static void
@@ -609,7 +483,7 @@ bl_cleanup_layoutcommit(struct nfs4_layoutcommit_data *lcdata)
 	struct pnfs_layout_hdr *lo = NFS_I(lcdata->args.inode)->layout;
 
 	dprintk("%s enter\n", __func__);
-	clean_pnfs_block_layoutupdate(BLK_LO2EXT(lo), &lcdata->args, lcdata->res.status);
+	ext_tree_mark_committed(BLK_LO2EXT(lo), lcdata->res.status);
 }
 
 static void free_blk_mountid(struct block_mount_id *mid)