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Commit 3d287de3 authored by Dmitry Monakhov's avatar Dmitry Monakhov Committed by Theodore Ts'o
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ext4: optimize orphan_list handling for ext4_setattr 



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: default avatarDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent beed5ecb

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))