btrfs: btrfs_check_shared should manage its own transaction (bb739cf0) · Commits · 戴 / test

fs/btrfs/backref.c

+19 −11

Original line number	Diff line number	Diff line
		@@ -1580,20 +1580,21 @@ int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
		/**
		* btrfs_check_shared - tell us whether an extent is shared
		*
		* @trans: optional trans handle
		*
		* btrfs_check_shared uses the backref walking code but will short
		* circuit as soon as it finds a root or inode that doesn't match the
		* one passed in. This provides a significant performance benefit for
		* callers (such as fiemap) which want to know whether the extent is
		* shared but do not need a ref count.
		*
		* This attempts to allocate a transaction in order to account for
		* delayed refs, but continues on even when the alloc fails.
		*
		* Return: 0 if extent is not shared, 1 if it is shared, < 0 on error.
		*/
		int btrfs_check_shared(struct btrfs_trans_handle *trans,
		struct btrfs_fs_info *fs_info, u64 root_objectid,
		u64 inum, u64 bytenr)
		int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr)
		{
		struct btrfs_fs_info *fs_info = root->fs_info;
		struct btrfs_trans_handle *trans;
		struct ulist *tmp = NULL;
		struct ulist *roots = NULL;
		struct ulist_iterator uiter;
		@@ -1609,14 +1610,18 @@ int btrfs_check_shared(struct btrfs_trans_handle *trans,
		return -ENOMEM;
		}

		if (trans)
		btrfs_get_tree_mod_seq(fs_info, &elem);
		else
		trans = btrfs_join_transaction(root);
		if (IS_ERR(trans)) {
		trans = NULL;
		down_read(&fs_info->commit_root_sem);
		} else {
		btrfs_get_tree_mod_seq(fs_info, &elem);
		}

		ULIST_ITER_INIT(&uiter);
		while (1) {
		ret = find_parent_nodes(trans, fs_info, bytenr, elem.seq, tmp,
		roots, NULL, root_objectid, inum, 1);
		roots, NULL, root->objectid, inum, 1);
		if (ret == BACKREF_FOUND_SHARED) {
		/* this is the only condition under which we return 1 */
		ret = 1;
		@@ -1631,10 +1636,13 @@ int btrfs_check_shared(struct btrfs_trans_handle *trans,
		bytenr = node->val;
		cond_resched();
		}
		if (trans)

		if (trans) {
		btrfs_put_tree_mod_seq(fs_info, &elem);
		else
		btrfs_end_transaction(trans);
		} else {
		up_read(&fs_info->commit_root_sem);
		}
		ulist_free(tmp);
		ulist_free(roots);
		return ret;

fs/btrfs/backref.h

+1 −3

Original line number	Diff line number	Diff line
		@@ -68,9 +68,7 @@ int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
		u64 start_off, struct btrfs_path *path,
		struct btrfs_inode_extref **ret_extref,
		u64 *found_off);
		int btrfs_check_shared(struct btrfs_trans_handle *trans,
		struct btrfs_fs_info *fs_info, u64 root_objectid,
		u64 inum, u64 bytenr);
		int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr);

		int __init btrfs_prelim_ref_init(void);
		void btrfs_prelim_ref_exit(void);

fs/btrfs/extent_io.c

+3 −19

Original line number	Diff line number	Diff line
		@@ -20,7 +20,6 @@
		#include "locking.h"
		#include "rcu-string.h"
		#include "backref.h"
		#include "transaction.h"

		static struct kmem_cache *extent_state_cache;
		static struct kmem_cache *extent_buffer_cache;
		@@ -4606,24 +4605,11 @@ int extent_fiemap(struct inode inode, struct fiemap_extent_info fieinfo,
		flags \|= (FIEMAP_EXTENT_DELALLOC \|
		FIEMAP_EXTENT_UNKNOWN);
		} else if (fieinfo->fi_extents_max) {
		struct btrfs_trans_handle *trans;

		u64 bytenr = em->block_start -
		(em->start - em->orig_start);

		disko = em->block_start + offset_in_extent;

		/*
		* We need a trans handle to get delayed refs
		*/
		trans = btrfs_join_transaction(root);
		/*
		* It's OK if we can't start a trans we can still check
		* from commit_root
		*/
		if (IS_ERR(trans))
		trans = NULL;

		/*
		* As btrfs supports shared space, this information
		* can be exported to userspace tools via
		@@ -4631,11 +4617,9 @@ int extent_fiemap(struct inode inode, struct fiemap_extent_info fieinfo,
		* then we're just getting a count and we can skip the
		* lookup stuff.
		*/
		ret = btrfs_check_shared(trans, root->fs_info,
		root->objectid,
		btrfs_ino(BTRFS_I(inode)), bytenr);
		if (trans)
		btrfs_end_transaction(trans);
		ret = btrfs_check_shared(root,
		btrfs_ino(BTRFS_I(inode)),
		bytenr);
		if (ret < 0)
		goto out_free;
		if (ret)

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