[PATCH] Optimize wait_sb_inodes()
hirofumi at mail.parknet.co.jp
Wed Jun 26 17:01:23 PDT 2013
Jörn Engel <joern at logfs.org> writes:
> Two things. Until there are actual implementations of
> s_op->wait_inodes, this is pure obfuscation. You already know this,
> of course.
On tux3, implementation of ->wait_inodes() is the following. Because
tux3 guarantees order what wait_sb_inodes() wants to check, like
+static void tux3_wait_inodes(struct super_block *sb)
+ * Since tux3 flushes whole delta and guarantee order of
+ * deltas, so tux3 doesn't need to wait inodes.
+ * Note, when we start to support direct I/O, we might have to
+ * revisit this to check in-progress direct I/O.
Another (untested) example for ext* would be like the following
static void ext4_wait_inodes(struct super_block *sb)
/* ->sync_fs() guarantees to wait all */
if (test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA)
/* FIXME: On data=ordered, we might be able to do something. */
> More interestingly, I personally hate methods with a default option if
> they are not implemented. Not too bad in this particular case, but
> the same pattern has burned me a number of times and wasted weeks of
> my life. So I would prefer to unconditionally call
> sb->s_op->wait_inodes(sb) and set it to wait_sb_inodes for all
> filesystems that don't have a smarter way to do things.
I don't have strong opinion about it though. Because the optimized
version is optional, this way might be safer.
Well, if there is the reason to push down, I will do it.
OGAWA Hirofumi <hirofumi at mail.parknet.co.jp>
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