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vfs: optimize touch_time() too

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Do a similar optimization as earlier for touch_atime.  Getting the lock in
mnt_get_write is relatively costly, so try all avenues to avoid it first.

This patch is careful to still only update inode fields inside the lock
region.

This didn't show up in benchmarks, but it's easy enough to do.

[[email protected]: fix typo in comment]
[[email protected]: fix inverted test of mnt_want_write_file()]
Signed-off-by: Andi Kleen <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Valerie Aurora <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Dave Hansen <[email protected]>
Signed-off-by: Hugh Dickins <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Al Viro <[email protected]>
This commit is contained in:
Andi Kleen 2009-09-18 13:05:48 -07:00 • committed by Al Viro
commit ce06e0b21d
1 changed files with 23 additions and 20 deletions
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43
fs/inode.c
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@ -1461,34 +1461,37 @@ void file_update_time(struct file *file)
{
struct inode *inode = file->f_path.dentry->d_inode;
struct timespec now;
int sync_it = 0;
int err;
enum { S_MTIME = 1, S_CTIME = 2, S_VERSION = 4 } sync_it = 0;
/* First try to exhaust all avenues to not sync */
if (IS_NOCMTIME(inode))
return;
err = mnt_want_write_file(file);
if (err)
now = current_fs_time(inode->i_sb);
if (!timespec_equal(&inode->i_mtime, &now))
sync_it = S_MTIME;
if (!timespec_equal(&inode->i_ctime, &now))
sync_it |= S_CTIME;
if (IS_I_VERSION(inode))
sync_it |= S_VERSION;
if (!sync_it)
return;
now = current_fs_time(inode->i_sb);
if (!timespec_equal(&inode->i_mtime, &now)) {
inode->i_mtime = now;
sync_it = 1;
}
/* Finally allowed to write? Takes lock. */
if (mnt_want_write_file(file))
return;
if (!timespec_equal(&inode->i_ctime, &now)) {
inode->i_ctime = now;
sync_it = 1;
}
if (IS_I_VERSION(inode)) {
/* Only change inode inside the lock region */
if (sync_it & S_VERSION)
inode_inc_iversion(inode);
sync_it = 1;
}
if (sync_it)
mark_inode_dirty_sync(inode);
if (sync_it & S_CTIME)
inode->i_ctime = now;
if (sync_it & S_MTIME)
inode->i_mtime = now;
mark_inode_dirty_sync(inode);
mnt_drop_write(file->f_path.mnt);
}
EXPORT_SYMBOL(file_update_time);