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authorAndi Kleen <andi@firstfloor.org>2009-09-18 13:05:48 -0700
committerAl Viro <viro@zeniv.linux.org.uk>2009-09-24 07:47:27 -0400
commitce06e0b21d6732a2bab10a585a3ec6909499be28 (patch)
tree5d796827ad968bf305c54a2dd7d6453a24e15344
parentb12536c27043f1c21195e587eb59950428326e22 (diff)
downloadop-kernel-dev-ce06e0b21d6732a2bab10a585a3ec6909499be28.zip
op-kernel-dev-ce06e0b21d6732a2bab10a585a3ec6909499be28.tar.gz
vfs: optimize touch_time() too
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. [akpm@linux-foundation.org: fix typo in comment] [hugh.dickins@tiscali.co.uk: fix inverted test of mnt_want_write_file()] Signed-off-by: Andi Kleen <ak@linux.intel.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Valerie Aurora <vaurora@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Dave Hansen <haveblue@us.ibm.com> Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--fs/inode.c43
1 files changed, 23 insertions, 20 deletions
diff --git a/fs/inode.c b/fs/inode.c
index 31168fd..4d8e3be 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -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)
- return;
-
now = current_fs_time(inode->i_sb);
- if (!timespec_equal(&inode->i_mtime, &now)) {
- inode->i_mtime = now;
- sync_it = 1;
- }
+ if (!timespec_equal(&inode->i_mtime, &now))
+ sync_it = S_MTIME;
- if (!timespec_equal(&inode->i_ctime, &now)) {
- inode->i_ctime = now;
- sync_it = 1;
- }
+ if (!timespec_equal(&inode->i_ctime, &now))
+ sync_it |= S_CTIME;
- if (IS_I_VERSION(inode)) {
- inode_inc_iversion(inode);
- sync_it = 1;
- }
+ if (IS_I_VERSION(inode))
+ sync_it |= S_VERSION;
- if (sync_it)
- mark_inode_dirty_sync(inode);
+ if (!sync_it)
+ return;
+
+ /* Finally allowed to write? Takes lock. */
+ if (mnt_want_write_file(file))
+ return;
+
+ /* Only change inode inside the lock region */
+ if (sync_it & S_VERSION)
+ inode_inc_iversion(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);
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