Skip to content

cloud-kernel
cloud-kernel

openanolis / cloud-kernel
大约 1 年 前同步成功

通知 158
Star 36
Fork 7
cloud-kernel
cloud-kernel

体验新版 GitCode，发现更多精彩内容 >>

切换分支/标签
  1. 18 4月, 2008 7 次提交
  3. 10 4月, 2008 1 次提交
  5. 07 2月, 2008 7 次提交
  7. 16 10月, 2007 1 次提交
  9. 15 10月, 2007 2 次提交
    • C
      [XFS] superblock endianess annotations · 2bdf7cd0
      由 Christoph Hellwig 提交于 
      Creates a new xfs_dsb_t that is __be annotated and keeps xfs_sb_t for the
incore one. xfs_xlatesb is renamed to xfs_sb_to_disk and only handles the
incore -> disk conversion. A new helper xfs_sb_from_disk handles the other
direction and doesn't need the slightly hacky table-driven approach
because we only ever read the full sb from disk.

The handling of shared r/o filesystems has been buggy on little endian
system and fixing this required shuffling around of some code in that
area.

SGI-PV: 968563
SGI-Modid: xfs-linux-melb:xfs-kern:29477a
Signed-off-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NDavid Chinner <dgc@sgi.com>
Signed-off-by: NTim Shimmin <tes@sgi.com>
      2bdf7cd0
    • C
      [XFS] dinode endianess annotations · 347d1c01
      由 Christoph Hellwig 提交于 
      Biggest bit is duplicating the dinode structure so we have one annotated for
native endianess and one for disk endianess. The other significant change
is that xfs_xlate_dinode_core is split into one helper per direction to
allow for proper annotations, everything else is trivial.

As a sidenode splitting out the incore dinode means we can move it into
xfs_inode.h in a later patch and severely improving on the include hell in
xfs.

SGI-PV: 968563
SGI-Modid: xfs-linux-melb:xfs-kern:29476a
Signed-off-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NDavid Chinner <dgc@sgi.com>
Signed-off-by: NTim Shimmin <tes@sgi.com>
      347d1c01
  11. 01 10月, 2007 2 次提交
  13. 20 9月, 2007 1 次提交
  15. 18 9月, 2007 1 次提交
  17. 05 9月, 2007 1 次提交
  19. 14 7月, 2007 1 次提交
    • D
      [XFS] Lazy Superblock Counters · 92821e2b
      由 David Chinner 提交于 
      When we have a couple of hundred transactions on the fly at once, they all
typically modify the on disk superblock in some way.
create/unclink/mkdir/rmdir modify inode counts, allocation/freeing modify
free block counts.

When these counts are modified in a transaction, they must eventually lock
the superblock buffer and apply the mods. The buffer then remains locked
until the transaction is committed into the incore log buffer. The result
of this is that with enough transactions on the fly the incore superblock
buffer becomes a bottleneck.

The result of contention on the incore superblock buffer is that
transaction rates fall - the more pressure that is put on the superblock
buffer, the slower things go.

The key to removing the contention is to not require the superblock fields
in question to be locked. We do that by not marking the superblock dirty
in the transaction. IOWs, we modify the incore superblock but do not
modify the cached superblock buffer. In short, we do not log superblock
modifications to critical fields in the superblock on every transaction.
In fact we only do it just before we write the superblock to disk every
sync period or just before unmount.

This creates an interesting problem - if we don't log or write out the
fields in every transaction, then how do the values get recovered after a
crash? the answer is simple - we keep enough duplicate, logged information
in other structures that we can reconstruct the correct count after log
recovery has been performed.

It is the AGF and AGI structures that contain the duplicate information;
after recovery, we walk every AGI and AGF and sum their individual
counters to get the correct value, and we do a transaction into the log to
correct them. An optimisation of this is that if we have a clean unmount
record, we know the value in the superblock is correct, so we can avoid
the summation walk under normal conditions and so mount/recovery times do
not change under normal operation.

One wrinkle that was discovered during development was that the blocks
used in the freespace btrees are never accounted for in the AGF counters.
This was once a valid optimisation to make; when the filesystem is full,
the free space btrees are empty and consume no space. Hence when it
matters, the "accounting" is correct. But that means the when we do the
AGF summations, we would not have a correct count and xfs_check would
complain. Hence a new counter was added to track the number of blocks used
by the free space btrees. This is an *on-disk format change*.

As a result of this, lazy superblock counters are a mkfs option and at the
moment on linux there is no way to convert an old filesystem. This is
possible - xfs_db can be used to twiddle the right bits and then
xfs_repair will do the format conversion for you. Similarly, you can
convert backwards as well. At some point we'll add functionality to
xfs_admin to do the bit twiddling easily....

SGI-PV: 964999
SGI-Modid: xfs-linux-melb:xfs-kern:28652a
Signed-off-by: NDavid Chinner <dgc@sgi.com>
Signed-off-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NTim Shimmin <tes@sgi.com>
      92821e2b
  21. 08 5月, 2007 3 次提交
  23. 10 2月, 2007 2 次提交
  25. 28 6月, 2006 1 次提交
  27. 20 6月, 2006 1 次提交
  29. 09 6月, 2006 4 次提交
  31. 29 3月, 2006 1 次提交
  33. 17 3月, 2006 1 次提交
  35. 11 1月, 2006 2 次提交
  37. 02 11月, 2005 1 次提交