Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

When mounting an ext4 filesystem, the following option are accepted:

(*) == default

extents			ext4 will use extents to address file data.  The

extents		(*)	ext4 will use extents to address file data.  The

			file system will no longer be mountable by ext3.

noextents		ext4 will not use extents for newly created files

journal_checksum	Enable checksumming of the journal transactions.

			This will allow the recovery code in e2fsck and the

			kernel to detect corruption in the kernel.  It is a

			compatible change and will be ignored by older kernels.

journal_async_commit	Commit block can be written to disk without waiting

			for descriptor blocks. If enabled older kernels cannot

			mount the device. This will enable 'journal_checksum'

			internally.

journal=update		Update the ext4 file system's journal to the current

			format.

			"nobh" option tries to avoid associating buffer

			heads (supported only for "writeback" mode).

mballoc		(*)	Use the multiple block allocator for block allocation

nomballoc		disabled multiple block allocator for block allocation.

stripe=n		Number of filesystem blocks that mballoc will try

			to use for allocation size and alignment. For RAID5/6

			systems this should be the number of data

			disks *  RAID chunk size in file system blocks.

Data Mode

---------

The   "procs_blocked" line gives  the  number of  processes currently blocked,

waiting for I/O to complete.

1.9 Ext4 file system parameters

------------------------------

Ext4 file system have one directory per partition under /proc/fs/ext4/

# ls /proc/fs/ext4/hdc/

group_prealloc  max_to_scan  mb_groups  mb_history  min_to_scan  order2_req

stats  stream_req

mb_groups:

This file gives the details of mutiblock allocator buddy cache of free blocks

mb_history:

Multiblock allocation history.

stats:

This file indicate whether the multiblock allocator should start collecting

statistics. The statistics are shown during unmount

group_prealloc:

The multiblock allocator normalize the block allocation request to

group_prealloc filesystem blocks if we don't have strip value set.

The stripe value can be specified at mount time or during mke2fs.

max_to_scan:

How long multiblock allocator can look for a best extent (in found extents)

min_to_scan:

How long multiblock allocator  must look for a best extent

order2_req:

Multiblock allocator use  2^N search using buddies only for requests greater

than or equal to order2_req. The request size is specfied in file system

blocks. A value of 2 indicate only if the requests are greater than or equal

to 4 blocks.

stream_req:

Files smaller than stream_req are served by the stream allocator, whose

purpose is to pack requests as close each to other as possible to

produce smooth I/O traffic. Avalue of 16 indicate that file smaller than 16

filesystem block size will use group based preallocation.

------------------------------------------------------------------------------

Summary

config JBD2

	tristate

	select CRC32

	help

	  This is a generic journaling layer for block devices that support

	  both 32-bit and 64-bit block numbers.  It is currently used by

	dentry->d_op = &afs_fs_dentry_operations;

	d_add(dentry, inode);

	_leave(" = 0 { vn=%u u=%u } -> { ino=%lu v=%lu }",

	_leave(" = 0 { vn=%u u=%u } -> { ino=%lu v=%llu }",

	       fid.vnode,

	       fid.unique,

	       dentry->d_inode->i_ino,

	       dentry->d_inode->i_version);

	       (unsigned long long)dentry->d_inode->i_version);

	return NULL;

}

		 * been deleted and replaced, and the original vnode ID has

		 * been reused */

		if (fid.unique != vnode->fid.unique) {

			_debug("%s: file deleted (uq %u -> %u I:%lu)",

			_debug("%s: file deleted (uq %u -> %u I:%llu)",

			       dentry->d_name.name, fid.unique,

			       vnode->fid.unique, dentry->d_inode->i_version);

			       vnode->fid.unique,

			       (unsigned long long)dentry->d_inode->i_version);

			spin_lock(&vnode->lock);

			set_bit(AFS_VNODE_DELETED, &vnode->flags);

			spin_unlock(&vnode->lock);

	inode = dentry->d_inode;

	_enter("{ ino=%lu v=%lu }", inode->i_ino, inode->i_version);

	_enter("{ ino=%lu v=%llu }", inode->i_ino,

		(unsigned long long)inode->i_version);

	generic_fillattr(inode, stat);

	return 0;