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ext4: optimize orphan_list handling for ext4_setattr

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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>
This commit is contained in:
Dmitry Monakhov 2010-10-27 22:08:46 -04:00 committed by Theodore Ts'o
parent beed5ecbaa
commit 3d287de3b8
1 changed files with 7 additions and 3 deletions
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10
fs/ext4/inode.c
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@ -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;
}
error = ext4_orphan_add(handle, inode);
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))