btrfsprogs/2105-move-min-resize-implementation-to-inspec.patch

From 670f1d97d708285bf3bb973c5c865fedcbbe9ab0 Mon Sep 17 00:00:00 2001
From: David Sterba <dsterba@suse.com>
Date: Mon, 20 Jul 2015 17:29:24 +0200
Subject: [PATCH 1/2] btrfs-progs: move min-resize implementation to
 inspect-internal

Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
---
 cmds-filesystem.c | 255 +-----------------------------------------------------
 cmds-inspect.c    | 241 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 242 insertions(+), 254 deletions(-)

diff --git a/cmds-filesystem.c b/cmds-filesystem.c
index b44a655..800aa4d 100644
--- a/cmds-filesystem.c
+++ b/cmds-filesystem.c
@@ -1271,264 +1271,14 @@ static int cmd_defrag(int argc, char **argv)
 }
 
 static const char * const cmd_resize_usage[] = {
-	"btrfs filesystem resize [devid:][+/-]<newsize>[kKmMgGtTpPeE]|[devid:]max|[devid:]get_min_size <path>",
+	"btrfs filesystem resize [devid:][+/-]<newsize>[kKmMgGtTpPeE]|[devid:]max <path>",
 	"Resize a filesystem",
 	"If 'max' is passed, the filesystem will occupy all available space",
 	"on the device 'devid'.",
-	"If 'get_min_size' is passed, return the minimum size the device can",
-	"be shrunk to.",
 	"[kK] means KiB, which denotes 1KiB = 1024B, 1MiB = 1024KiB, etc.",
 	NULL
 };
 
-struct dev_extent_elem {
-	u64 start;
-	/* inclusive end */
-	u64 end;
-	struct list_head list;
-};
-
-static int add_dev_extent(struct list_head *list,
-			  const u64 start, const u64 end,
-			  const int append)
-{
-	struct dev_extent_elem *e;
-
-	e = malloc(sizeof(*e));
-	if (!e)
-		return -ENOMEM;
-
-	e->start = start;
-	e->end = end;
-
-	if (append)
-		list_add_tail(&e->list, list);
-	else
-		list_add(&e->list, list);
-
-	return 0;
-}
-
-static void free_dev_extent_list(struct list_head *list)
-{
-	while (!list_empty(list)) {
-		struct dev_extent_elem *e;
-
-		e = list_first_entry(list, struct dev_extent_elem, list);
-		list_del(&e->list);
-		free(e);
-	}
-}
-
-static int hole_includes_sb_mirror(const u64 start, const u64 end)
-{
-	int i;
-	int ret = 0;
-
-	for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
-		u64 bytenr = btrfs_sb_offset(i);
-
-		if (bytenr >= start && bytenr <= end) {
-			ret = 1;
-			break;
-		}
-	}
-
-	return ret;
-}
-
-static void adjust_dev_min_size(struct list_head *extents,
-				struct list_head *holes,
-				u64 *min_size)
-{
-	/*
-	 * If relocation of the block group of a device extent must happen (see
-	 * below) scratch space is used for the relocation. So track here the
-	 * size of the largest device extent that has to be relocated. We track
-	 * only the largest and not the sum of the sizes of all relocated block
-	 * groups because after each block group is relocated the running
-	 * transaction is committed so that pinned space is released.
-	 */
-	u64 scratch_space = 0;
-
-	/*
-	 * List of device extents is sorted by descending order of the extent's
-	 * end offset. If some extent goes beyond the computed minimum size,
-	 * which initially matches the sum of the lenghts of all extents,
-	 * we need to check if the extent can be relocated to an hole in the
-	 * device between [0, *min_size[ (which is what the resize ioctl does).
-	 */
-	while (!list_empty(extents)) {
-		struct dev_extent_elem *e;
-		struct dev_extent_elem *h;
-		int found = 0;
-		u64 extent_len;
-		u64 hole_len = 0;
-
-		e = list_first_entry(extents, struct dev_extent_elem, list);
-		if (e->end <= *min_size)
-			break;
-
-		/*
-		 * Our extent goes beyond the computed *min_size. See if we can
-		 * find a hole large enough to relocate it to. If not we must stop
-		 * and set *min_size to the end of the extent.
-		 */
-		extent_len = e->end - e->start + 1;
-		list_for_each_entry(h, holes, list) {
-			hole_len = h->end - h->start + 1;
-			if (hole_len >= extent_len) {
-				found = 1;
-				break;
-			}
-		}
-
-		if (!found) {
-			*min_size = e->end + 1;
-			break;
-		}
-
-		/*
-		 * If the hole found contains the location for a superblock
-		 * mirror, we are pessimistic and require allocating one
-		 * more extent of the same size. This is because the block
-		 * group could be in the worst case used by a single extent
-		 * with a size >= (block_group.length - superblock.size).
-		 */
-		if (hole_includes_sb_mirror(h->start,
-					    h->start + extent_len - 1))
-			*min_size += extent_len;
-
-		if (hole_len > extent_len) {
-			h->start += extent_len;
-		} else {
-			list_del(&h->list);
-			free(h);
-		}
-
-		list_del(&e->list);
-		free(e);
-
-		if (extent_len > scratch_space)
-			scratch_space = extent_len;
-	}
-
-	if (scratch_space) {
-		*min_size += scratch_space;
-		/*
-		 * Chunk allocation requires inserting/updating items in the
-		 * chunk tree, so often this can lead to the need of allocating
-		 * a new system chunk too, which has a maximum size of 32Mb.
-		 */
-		*min_size += 32 * 1024 * 1024;
-	}
-}
-
-static int get_min_size(int fd, DIR *dirstream, const char *amount)
-{
-	int ret = 1;
-	char *p = strstr(amount, ":");
-	u64 devid = 1;
-	/*
-	 * Device allocations starts at 1Mb or at the value passed through the
-	 * mount option alloc_start if it's bigger than 1Mb. The alloc_start
-	 * option is used for debugging and testing only, and recently the
-	 * possibility of deprecating/removing it has been discussed, so we
-	 * ignore it here.
-	 */
-	u64 min_size = 1 * 1024 * 1024ull;
-	struct btrfs_ioctl_search_args args;
-	struct btrfs_ioctl_search_key *sk = &args.key;
-	u64 last_pos = (u64)-1;
-	LIST_HEAD(extents);
-	LIST_HEAD(holes);
-
-	if (p && sscanf(amount, "%llu:get_min_size", &devid) != 1) {
-		fprintf(stderr, "Invalid parameter: %s\n", amount);
-		goto out;
-	}
-
-	memset(&args, 0, sizeof(args));
-	sk->tree_id = BTRFS_DEV_TREE_OBJECTID;
-	sk->min_objectid = devid;
-	sk->max_objectid = devid;
-	sk->max_type = BTRFS_DEV_EXTENT_KEY;
-	sk->min_type = BTRFS_DEV_EXTENT_KEY;
-	sk->min_offset = 0;
-	sk->max_offset = (u64)-1;
-	sk->min_transid = 0;
-	sk->max_transid = (u64)-1;
-	sk->nr_items = 4096;
-
-	while (1) {
-		int i;
-		struct btrfs_ioctl_search_header *sh;
-		unsigned long off = 0;
-
-		ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args);
-		if (ret < 0) {
-			fprintf(stderr,
-				"Error invoking tree search ioctl: %s\n",
-				strerror(errno));
-			ret = 1;
-			goto out;
-		}
-
-		if (sk->nr_items == 0)
-			break;
-
-		for (i = 0; i < sk->nr_items; i++) {
-			struct btrfs_dev_extent *extent;
-			u64 len;
-
-			sh = (struct btrfs_ioctl_search_header *)(args.buf +
-								  off);
-			off += sizeof(*sh);
-			extent = (struct btrfs_dev_extent *)(args.buf + off);
-			off += sh->len;
-
-			sk->min_objectid = sh->objectid;
-			sk->min_type = sh->type;
-			sk->min_offset = sh->offset + 1;
-
-			if (sh->objectid != devid ||
-			    sh->type != BTRFS_DEV_EXTENT_KEY)
-				continue;
-
-			len = btrfs_stack_dev_extent_length(extent);
-			min_size += len;
-			ret = add_dev_extent(&extents, sh->offset,
-					     sh->offset + len - 1, 0);
-
-			if (!ret && last_pos != (u64)-1 &&
-			    last_pos != sh->offset)
-				ret = add_dev_extent(&holes, last_pos,
-						     sh->offset - 1, 1);
-			if (ret) {
-				fprintf(stderr, "Error: %s\n", strerror(-ret));
-				ret = 1;
-				goto out;
-			}
-
-			last_pos = sh->offset + len;
-		}
-
-		if (sk->min_type != BTRFS_DEV_EXTENT_KEY ||
-		    sk->min_objectid != devid)
-			break;
-	}
-
-	adjust_dev_min_size(&extents, &holes, &min_size);
-	printf("%llu bytes (%s)\n", min_size, pretty_size(min_size));
-	ret = 0;
-out:
-	close_file_or_dir(fd, dirstream);
-	free_dev_extent_list(&extents);
-	free_dev_extent_list(&holes);
-
-	return ret;
-}
-
 static int cmd_resize(int argc, char **argv)
 {
 	struct btrfs_ioctl_vol_args	args;
@@ -1570,9 +1320,6 @@ static int cmd_resize(int argc, char **argv)
 		return 1;
 	}
 
-	if (strstr(amount, "get_min_size"))
-		return get_min_size(fd, dirstream, amount);
-
 	printf("Resize '%s' of '%s'\n", path, amount);
 	memset(&args, 0, sizeof(args));
 	strncpy_null(args.name, amount);
diff --git a/cmds-inspect.c b/cmds-inspect.c
index 71451fe..05f1ccf 100644
--- a/cmds-inspect.c
+++ b/cmds-inspect.c
@@ -338,6 +338,247 @@ out:
 	return !!ret;
 }
 
+struct dev_extent_elem {
+	u64 start;
+	/* inclusive end */
+	u64 end;
+	struct list_head list;
+};
+
+static int add_dev_extent(struct list_head *list,
+			  const u64 start, const u64 end,
+			  const int append)
+{
+	struct dev_extent_elem *e;
+
+	e = malloc(sizeof(*e));
+	if (!e)
+		return -ENOMEM;
+
+	e->start = start;
+	e->end = end;
+
+	if (append)
+		list_add_tail(&e->list, list);
+	else
+		list_add(&e->list, list);
+
+	return 0;
+}
+
+static void free_dev_extent_list(struct list_head *list)
+{
+	while (!list_empty(list)) {
+		struct dev_extent_elem *e;
+
+		e = list_first_entry(list, struct dev_extent_elem, list);
+		list_del(&e->list);
+		free(e);
+	}
+}
+
+static int hole_includes_sb_mirror(const u64 start, const u64 end)
+{
+	int i;
+	int ret = 0;
+
+	for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
+		u64 bytenr = btrfs_sb_offset(i);
+
+		if (bytenr >= start && bytenr <= end) {
+			ret = 1;
+			break;
+		}
+	}
+
+	return ret;
+}
+
+static void adjust_dev_min_size(struct list_head *extents,
+				struct list_head *holes,
+				u64 *min_size)
+{
+	/*
+	 * If relocation of the block group of a device extent must happen (see
+	 * below) scratch space is used for the relocation. So track here the
+	 * size of the largest device extent that has to be relocated. We track
+	 * only the largest and not the sum of the sizes of all relocated block
+	 * groups because after each block group is relocated the running
+	 * transaction is committed so that pinned space is released.
+	 */
+	u64 scratch_space = 0;
+
+	/*
+	 * List of device extents is sorted by descending order of the extent's
+	 * end offset. If some extent goes beyond the computed minimum size,
+	 * which initially matches the sum of the lenghts of all extents,
+	 * we need to check if the extent can be relocated to an hole in the
+	 * device between [0, *min_size[ (which is what the resize ioctl does).
+	 */
+	while (!list_empty(extents)) {
+		struct dev_extent_elem *e;
+		struct dev_extent_elem *h;
+		int found = 0;
+		u64 extent_len;
+		u64 hole_len = 0;
+
+		e = list_first_entry(extents, struct dev_extent_elem, list);
+		if (e->end <= *min_size)
+			break;
+
+		/*
+		 * Our extent goes beyond the computed *min_size. See if we can
+		 * find a hole large enough to relocate it to. If not we must stop
+		 * and set *min_size to the end of the extent.
+		 */
+		extent_len = e->end - e->start + 1;
+		list_for_each_entry(h, holes, list) {
+			hole_len = h->end - h->start + 1;
+			if (hole_len >= extent_len) {
+				found = 1;
+				break;
+			}
+		}
+
+		if (!found) {
+			*min_size = e->end + 1;
+			break;
+		}
+
+		/*
+		 * If the hole found contains the location for a superblock
+		 * mirror, we are pessimistic and require allocating one
+		 * more extent of the same size. This is because the block
+		 * group could be in the worst case used by a single extent
+		 * with a size >= (block_group.length - superblock.size).
+		 */
+		if (hole_includes_sb_mirror(h->start,
+					    h->start + extent_len - 1))
+			*min_size += extent_len;
+
+		if (hole_len > extent_len) {
+			h->start += extent_len;
+		} else {
+			list_del(&h->list);
+			free(h);
+		}
+
+		list_del(&e->list);
+		free(e);
+
+		if (extent_len > scratch_space)
+			scratch_space = extent_len;
+	}
+
+	if (scratch_space) {
+		*min_size += scratch_space;
+		/*
+		 * Chunk allocation requires inserting/updating items in the
+		 * chunk tree, so often this can lead to the need of allocating
+		 * a new system chunk too, which has a maximum size of 32Mb.
+		 */
+		*min_size += 32 * 1024 * 1024;
+	}
+}
+
+static int get_min_size(int fd, DIR *dirstream, u64 devid)
+{
+	int ret = 1;
+	/*
+	 * Device allocations starts at 1Mb or at the value passed through the
+	 * mount option alloc_start if it's bigger than 1Mb. The alloc_start
+	 * option is used for debugging and testing only, and recently the
+	 * possibility of deprecating/removing it has been discussed, so we
+	 * ignore it here.
+	 */
+	u64 min_size = 1 * 1024 * 1024ull;
+	struct btrfs_ioctl_search_args args;
+	struct btrfs_ioctl_search_key *sk = &args.key;
+	u64 last_pos = (u64)-1;
+	LIST_HEAD(extents);
+	LIST_HEAD(holes);
+
+	memset(&args, 0, sizeof(args));
+	sk->tree_id = BTRFS_DEV_TREE_OBJECTID;
+	sk->min_objectid = devid;
+	sk->max_objectid = devid;
+	sk->max_type = BTRFS_DEV_EXTENT_KEY;
+	sk->min_type = BTRFS_DEV_EXTENT_KEY;
+	sk->min_offset = 0;
+	sk->max_offset = (u64)-1;
+	sk->min_transid = 0;
+	sk->max_transid = (u64)-1;
+	sk->nr_items = 4096;
+
+	while (1) {
+		int i;
+		struct btrfs_ioctl_search_header *sh;
+		unsigned long off = 0;
+
+		ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args);
+		if (ret < 0) {
+			fprintf(stderr,
+				"Error invoking tree search ioctl: %s\n",
+				strerror(errno));
+			ret = 1;
+			goto out;
+		}
+
+		if (sk->nr_items == 0)
+			break;
+
+		for (i = 0; i < sk->nr_items; i++) {
+			struct btrfs_dev_extent *extent;
+			u64 len;
+
+			sh = (struct btrfs_ioctl_search_header *)(args.buf +
+								  off);
+			off += sizeof(*sh);
+			extent = (struct btrfs_dev_extent *)(args.buf + off);
+			off += sh->len;
+
+			sk->min_objectid = sh->objectid;
+			sk->min_type = sh->type;
+			sk->min_offset = sh->offset + 1;
+
+			if (sh->objectid != devid ||
+			    sh->type != BTRFS_DEV_EXTENT_KEY)
+				continue;
+
+			len = btrfs_stack_dev_extent_length(extent);
+			min_size += len;
+			ret = add_dev_extent(&extents, sh->offset,
+					     sh->offset + len - 1, 0);
+
+			if (!ret && last_pos != (u64)-1 &&
+			    last_pos != sh->offset)
+				ret = add_dev_extent(&holes, last_pos,
+						     sh->offset - 1, 1);
+			if (ret) {
+				fprintf(stderr, "Error: %s\n", strerror(-ret));
+				ret = 1;
+				goto out;
+			}
+
+			last_pos = sh->offset + len;
+		}
+
+		if (sk->min_type != BTRFS_DEV_EXTENT_KEY ||
+		    sk->min_objectid != devid)
+			break;
+	}
+
+	adjust_dev_min_size(&extents, &holes, &min_size);
+	printf("%llu bytes (%s)\n", min_size, pretty_size(min_size));
+	ret = 0;
+out:
+	close_file_or_dir(fd, dirstream);
+	free_dev_extent_list(&extents);
+	free_dev_extent_list(&holes);
+
+	return ret;
+}
+
 static const char inspect_cmd_group_info[] =
 "query various internal information";
 
-- 
1.8.4.5