On 01/12/2012 09:01 PM, Andreas Dilger wrote:
On 2012-01-12, at 8:01 PM, Allison Henderson wrote:
I know this is an old topic, but I am poking it again because I've had some work items wrap up, and Im planning on picking up on this one again. I am thinking about implementing extent locks to replace i_mutex. So I just wanted to touch base with folks and see what people are working on because I know there were some folks out there that were thing about doing similar solutions.
A while ago I had done some investigation on where i_mutex is currently used, so I did a review and updated my list. Only one thing had been removed, but I will leave the list here since it was a while ago. Let me know if anyone has been working on similar concept. Thx!
The in-ext4 users appear to all be file IO related, while the VFS functions
are mostly directory related, though I don't see any mention of the callers
of ext4_mkdir() or ext4_mknod() or ext4_create()?
Hmm, those ones didnt turn up when I was looking for i_mutex locking.
Though it would make sense that they would be locked. Did I over look
it in a helper function somewhere?
For Lustre we developed a patch that allows parallel metadata operations on
directories (e.g. concurrent lookup, mkdir, rmdir, create, unlink in a single
directory) which would replace i_mutex for the namespace operations. Patch:
http://git.whamcloud.com/?p=fs/lustre-release.git;a=blob;f=ldiskfs/kernel_patches/patches/ext4_pdirop-rhel6.patch;hb=HEAD
though this in itself isn't enough to allow the VFS to do parallel directory
operations. We're of course also interested in parallel file IO operations
through the VFS for the client, though this hasn't been a focus of ours since
we typically have a large number of clients doing IO concurrently.
I see, I will take a look at it, maybe there will be some things I can
borrow from it. Thx!
List of ext4 functions that lock i_mutex:
ext4_sync_file
ext4_fallocate
ext4_move_extents via two helper routines:
mext_inode_double_lock and mext_inode_double_unlock
ext4_ioctl (for the EXT4_IOC_SETFLAGS ioctl)
ext4_quota_write
ext4_llseek
ext4_end_io_work
ext4_ind_direct_IO (only while calling ext4_flush_completed_IO)
Functions called by vfs with i_mutex locked:
ext4_setattr
ext4_da_writepages
ext4_rmdir
ext4_unlink
ext4_symlink
ext4_link
ext4_rename
ext4_get_block
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Cheers, Andreas
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
