ext4: optimize orphan_list handling for ext4_setattr (3d287de3) · Commits · 戴 / test

Surprisingly chown() on ext4 is not SMP scalable operation. Due to unconditional orphan_del(NULL, inode) in ext4_setattr() result in significant performance overhead because of global orphan mutex, especially in no-journal mode (where orphan_add() is noop). It is possible to skip explicit orphan_del if possible. Results of fchown() micro-benchmark in no-journal mode while (1) { iteration++; fchown(fd, uid, gid); fchown(fd, uid + 1, gid + 1) } measured: iterations per millisecond | nr_tasks | w/o patch | with patch | | 1 | 142 | 185 | | 4 | 109 | 642 | Signed-off-by:

Dmitry Monakhov <dmonakhov@openvz.org> Signed-off-by:

"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/inode.c

+7 −3

Original line number	Diff line number	Diff line
		@@ -5281,6 +5281,7 @@ int ext4_setattr(struct dentry dentry, struct iattr attr)
		{
		struct inode *inode = dentry->d_inode;
		int error, rc = 0;
		int orphan = 0;
		const unsigned int ia_valid = attr->ia_valid;

		error = inode_change_ok(inode, attr);
		@@ -5336,8 +5337,10 @@ int ext4_setattr(struct dentry dentry, struct iattr attr)
		error = PTR_ERR(handle);
		goto err_out;
		}

		if (ext4_handle_valid(handle)) {
		error = ext4_orphan_add(handle, inode);
		orphan = 1;
		}
		EXT4_I(inode)->i_disksize = attr->ia_size;
		rc = ext4_mark_inode_dirty(handle, inode);
		if (!error)
		@@ -5355,6 +5358,7 @@ int ext4_setattr(struct dentry dentry, struct iattr attr)
		goto err_out;
		}
		ext4_orphan_del(handle, inode);
		orphan = 0;
		ext4_journal_stop(handle);
		goto err_out;
		}
		@@ -5377,7 +5381,7 @@ int ext4_setattr(struct dentry dentry, struct iattr attr)
		* If the call to ext4_truncate failed to get a transaction handle at
		* all, we need to clean up the in-core orphan list manually.
		*/
		if (inode->i_nlink)
		if (orphan && inode->i_nlink)
		ext4_orphan_del(NULL, inode);

		if (!rc && (ia_valid & ATTR_MODE))

Admin message