Btrfs: support swap files (ed46ff3d) · Commits · 戴 / test

fs/btrfs/inode.c

+340 −0

Original line number	Diff line number	Diff line
		@@ -27,6 +27,7 @@
		#include <linux/uio.h>
		#include <linux/magic.h>
		#include <linux/iversion.h>
		#include <linux/swap.h>
		#include <asm/unaligned.h>
		#include "ctree.h"
		#include "disk-io.h"
		@@ -10460,6 +10461,343 @@ void btrfs_set_range_writeback(struct extent_io_tree *tree, u64 start, u64 end)
		}
		}

		#ifdef CONFIG_SWAP
		/*
		* Add an entry indicating a block group or device which is pinned by a
		* swapfile. Returns 0 on success, 1 if there is already an entry for it, or a
		* negative errno on failure.
		*/
		static int btrfs_add_swapfile_pin(struct inode inode, void ptr,
		bool is_block_group)
		{
		struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
		struct btrfs_swapfile_pin sp, entry;
		struct rb_node **p;
		struct rb_node *parent = NULL;

		sp = kmalloc(sizeof(*sp), GFP_NOFS);
		if (!sp)
		return -ENOMEM;
		sp->ptr = ptr;
		sp->inode = inode;
		sp->is_block_group = is_block_group;

		spin_lock(&fs_info->swapfile_pins_lock);
		p = &fs_info->swapfile_pins.rb_node;
		while (*p) {
		parent = *p;
		entry = rb_entry(parent, struct btrfs_swapfile_pin, node);
		if (sp->ptr < entry->ptr \|\|
		(sp->ptr == entry->ptr && sp->inode < entry->inode)) {
		p = &(*p)->rb_left;
		} else if (sp->ptr > entry->ptr \|\|
		(sp->ptr == entry->ptr && sp->inode > entry->inode)) {
		p = &(*p)->rb_right;
		} else {
		spin_unlock(&fs_info->swapfile_pins_lock);
		kfree(sp);
		return 1;
		}
		}
		rb_link_node(&sp->node, parent, p);
		rb_insert_color(&sp->node, &fs_info->swapfile_pins);
		spin_unlock(&fs_info->swapfile_pins_lock);
		return 0;
		}

		/* Free all of the entries pinned by this swapfile. */
		static void btrfs_free_swapfile_pins(struct inode *inode)
		{
		struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
		struct btrfs_swapfile_pin *sp;
		struct rb_node node, next;

		spin_lock(&fs_info->swapfile_pins_lock);
		node = rb_first(&fs_info->swapfile_pins);
		while (node) {
		next = rb_next(node);
		sp = rb_entry(node, struct btrfs_swapfile_pin, node);
		if (sp->inode == inode) {
		rb_erase(&sp->node, &fs_info->swapfile_pins);
		if (sp->is_block_group)
		btrfs_put_block_group(sp->ptr);
		kfree(sp);
		}
		node = next;
		}
		spin_unlock(&fs_info->swapfile_pins_lock);
		}

		struct btrfs_swap_info {
		u64 start;
		u64 block_start;
		u64 block_len;
		u64 lowest_ppage;
		u64 highest_ppage;
		unsigned long nr_pages;
		int nr_extents;
		};

		static int btrfs_add_swap_extent(struct swap_info_struct *sis,
		struct btrfs_swap_info *bsi)
		{
		unsigned long nr_pages;
		u64 first_ppage, first_ppage_reported, next_ppage;
		int ret;

		first_ppage = ALIGN(bsi->block_start, PAGE_SIZE) >> PAGE_SHIFT;
		next_ppage = ALIGN_DOWN(bsi->block_start + bsi->block_len,
		PAGE_SIZE) >> PAGE_SHIFT;

		if (first_ppage >= next_ppage)
		return 0;
		nr_pages = next_ppage - first_ppage;

		first_ppage_reported = first_ppage;
		if (bsi->start == 0)
		first_ppage_reported++;
		if (bsi->lowest_ppage > first_ppage_reported)
		bsi->lowest_ppage = first_ppage_reported;
		if (bsi->highest_ppage < (next_ppage - 1))
		bsi->highest_ppage = next_ppage - 1;

		ret = add_swap_extent(sis, bsi->nr_pages, nr_pages, first_ppage);
		if (ret < 0)
		return ret;
		bsi->nr_extents += ret;
		bsi->nr_pages += nr_pages;
		return 0;
		}

		static void btrfs_swap_deactivate(struct file *file)
		{
		struct inode *inode = file_inode(file);

		btrfs_free_swapfile_pins(inode);
		atomic_dec(&BTRFS_I(inode)->root->nr_swapfiles);
		}

		static int btrfs_swap_activate(struct swap_info_struct sis, struct file file,
		sector_t *span)
		{
		struct inode *inode = file_inode(file);
		struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
		struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
		struct extent_state *cached_state = NULL;
		struct extent_map *em = NULL;
		struct btrfs_device *device = NULL;
		struct btrfs_swap_info bsi = {
		.lowest_ppage = (sector_t)-1ULL,
		};
		int ret = 0;
		u64 isize;
		u64 start;

		/*
		* If the swap file was just created, make sure delalloc is done. If the
		* file changes again after this, the user is doing something stupid and
		* we don't really care.
		*/
		ret = btrfs_wait_ordered_range(inode, 0, (u64)-1);
		if (ret)
		return ret;

		/*
		* The inode is locked, so these flags won't change after we check them.
		*/
		if (BTRFS_I(inode)->flags & BTRFS_INODE_COMPRESS) {
		btrfs_warn(fs_info, "swapfile must not be compressed");
		return -EINVAL;
		}
		if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW)) {
		btrfs_warn(fs_info, "swapfile must not be copy-on-write");
		return -EINVAL;
		}
		if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
		btrfs_warn(fs_info, "swapfile must not be checksummed");
		return -EINVAL;
		}

		/*
		* Balance or device remove/replace/resize can move stuff around from
		* under us. The EXCL_OP flag makes sure they aren't running/won't run
		* concurrently while we are mapping the swap extents, and
		* fs_info->swapfile_pins prevents them from running while the swap file
		* is active and moving the extents. Note that this also prevents a
		* concurrent device add which isn't actually necessary, but it's not
		* really worth the trouble to allow it.
		*/
		if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
		btrfs_warn(fs_info,
		"cannot activate swapfile while exclusive operation is running");
		return -EBUSY;
		}
		/*
		* Snapshots can create extents which require COW even if NODATACOW is
		* set. We use this counter to prevent snapshots. We must increment it
		* before walking the extents because we don't want a concurrent
		* snapshot to run after we've already checked the extents.
		*/
		atomic_inc(&BTRFS_I(inode)->root->nr_swapfiles);

		isize = ALIGN_DOWN(inode->i_size, fs_info->sectorsize);

		lock_extent_bits(io_tree, 0, isize - 1, &cached_state);
		start = 0;
		while (start < isize) {
		u64 logical_block_start, physical_block_start;
		struct btrfs_block_group_cache *bg;
		u64 len = isize - start;

		em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, start, len, 0);
		if (IS_ERR(em)) {
		ret = PTR_ERR(em);
		goto out;
		}

		if (em->block_start == EXTENT_MAP_HOLE) {
		btrfs_warn(fs_info, "swapfile must not have holes");
		ret = -EINVAL;
		goto out;
		}
		if (em->block_start == EXTENT_MAP_INLINE) {
		/*
		* It's unlikely we'll ever actually find ourselves
		* here, as a file small enough to fit inline won't be
		* big enough to store more than the swap header, but in
		* case something changes in the future, let's catch it
		* here rather than later.
		*/
		btrfs_warn(fs_info, "swapfile must not be inline");
		ret = -EINVAL;
		goto out;
		}
		if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
		btrfs_warn(fs_info, "swapfile must not be compressed");
		ret = -EINVAL;
		goto out;
		}

		logical_block_start = em->block_start + (start - em->start);
		len = min(len, em->len - (start - em->start));
		free_extent_map(em);
		em = NULL;

		ret = can_nocow_extent(inode, start, &len, NULL, NULL, NULL);
		if (ret < 0) {
		goto out;
		} else if (ret) {
		ret = 0;
		} else {
		btrfs_warn(fs_info,
		"swapfile must not be copy-on-write");
		ret = -EINVAL;
		goto out;
		}

		em = btrfs_get_chunk_map(fs_info, logical_block_start, len);
		if (IS_ERR(em)) {
		ret = PTR_ERR(em);
		goto out;
		}

		if (em->map_lookup->type & BTRFS_BLOCK_GROUP_PROFILE_MASK) {
		btrfs_warn(fs_info,
		"swapfile must have single data profile");
		ret = -EINVAL;
		goto out;
		}

		if (device == NULL) {
		device = em->map_lookup->stripes[0].dev;
		ret = btrfs_add_swapfile_pin(inode, device, false);
		if (ret == 1)
		ret = 0;
		else if (ret)
		goto out;
		} else if (device != em->map_lookup->stripes[0].dev) {
		btrfs_warn(fs_info, "swapfile must be on one device");
		ret = -EINVAL;
		goto out;
		}

		physical_block_start = (em->map_lookup->stripes[0].physical +
		(logical_block_start - em->start));
		len = min(len, em->len - (logical_block_start - em->start));
		free_extent_map(em);
		em = NULL;

		bg = btrfs_lookup_block_group(fs_info, logical_block_start);
		if (!bg) {
		btrfs_warn(fs_info,
		"could not find block group containing swapfile");
		ret = -EINVAL;
		goto out;
		}

		ret = btrfs_add_swapfile_pin(inode, bg, true);
		if (ret) {
		btrfs_put_block_group(bg);
		if (ret == 1)
		ret = 0;
		else
		goto out;
		}

		if (bsi.block_len &&
		bsi.block_start + bsi.block_len == physical_block_start) {
		bsi.block_len += len;
		} else {
		if (bsi.block_len) {
		ret = btrfs_add_swap_extent(sis, &bsi);
		if (ret)
		goto out;
		}
		bsi.start = start;
		bsi.block_start = physical_block_start;
		bsi.block_len = len;
		}

		start += len;
		}

		if (bsi.block_len)
		ret = btrfs_add_swap_extent(sis, &bsi);

		out:
		if (!IS_ERR_OR_NULL(em))
		free_extent_map(em);

		unlock_extent_cached(io_tree, 0, isize - 1, &cached_state);

		if (ret)
		btrfs_swap_deactivate(file);

		clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);

		if (ret)
		return ret;

		if (device)
		sis->bdev = device->bdev;
		*span = bsi.highest_ppage - bsi.lowest_ppage + 1;
		sis->max = bsi.nr_pages;
		sis->pages = bsi.nr_pages - 1;
		sis->highest_bit = bsi.nr_pages - 1;
		return bsi.nr_extents;
		}
		#else
		static void btrfs_swap_deactivate(struct file *file)
		{
		}

		static int btrfs_swap_activate(struct swap_info_struct sis, struct file file,
		sector_t *span)
		{
		return -EOPNOTSUPP;
		}
		#endif

		static const struct inode_operations btrfs_dir_inode_operations = {
		.getattr = btrfs_getattr,
		.lookup = btrfs_lookup,
		@@ -10527,6 +10865,8 @@ static const struct address_space_operations btrfs_aops = {
		.releasepage = btrfs_releasepage,
		.set_page_dirty = btrfs_set_page_dirty,
		.error_remove_page = generic_error_remove_page,
		.swap_activate = btrfs_swap_activate,
		.swap_deactivate = btrfs_swap_deactivate,
		};

		static const struct inode_operations btrfs_file_inode_operations = {

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