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  1. 28 4月, 2013 10 次提交
    • D
      xfs: add CRC protection to remote attributes · d2e448d5
      由 Dave Chinner 提交于 
      There are two ways of doing this - the first is to add a CRC to the
remote attribute entry in the attribute block. The second is to
treat them similar to the remote symlink, where each fragment has
it's own header and identifies fragment location in the attribute.

The problem with the CRC in the remote attr entry is that we cannot
identify the owner of the metadata from the metadata blocks
themselves, or where the blocks fit into the remote attribute. The
down side to this approach is that we never know when the attribute
has been read from disk or not and so we have to verify it every
time it is read, and we must calculate it during the create
transaction and log it. We do not log CRCs for any other metadata,
and so this creates a unique set of coherency problems that, in
general, are best avoided.

Adding an identifying header to each allocated block allows us to
identify each fragment and where in the attribute it is located. It
enables us to rebuild the remote attribute from just the raw blocks
containing the attribute. It also provides us to do per-block CRCs
verification at IO time rather than during the transaction context
that creates it or every time it is read into a user buffer. Hence
it avoids all the problems that an external, logged CRC has, and
provides all the benefits of self identifying metadata.

The only complexity is that we have to add a header per fragment,
and we don't know how many fragments will be needed prior to
allocations. If we take the symlink example, the header is 56 bytes
and hence for a 4k block size filesystem, in the worst case 16
headers requires 1 extra block for the 64k attribute data. For 512
byte filesystems the worst case is an extra block for every 9
fragments (i.e. 16 extra blocks in the worse case). This will be
very rare and so it's not really a major concern.

Because allocation is done in two steps - the first finds a hole
large enough in the attribute file, the second does the allocation -
we only need to find a hole big enough for a worst case allocation.
We only need to allocate enough extra blocks for number of headers
required by the fragments, and we can calculate that as we go....

Hence it really only makes sense to use the same model as for
symlinks - it doesn't add that much complexity, does not require an
attribute tree format change, and does not require logging
calculated CRC values.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NBen Myers <bpm@sgi.com>
Signed-off-by: NBen Myers <bpm@sgi.com>
      d2e448d5
    • D
      xfs: split remote attribute code out · 95920cd6
      由 Dave Chinner 提交于 
      Adding CRC support to remote attributes adds a significant amount of
remote attribute specific code. Split the existing remote attribute
code out into it's own file so that all the relevant remote
attribute code is in a single, easy to find place.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NBen Myers <bpm@sgi.com>
Signed-off-by: NBen Myers <bpm@sgi.com>
      95920cd6
    • D
      xfs: add CRCs to attr leaf blocks · 517c2220
      由 Dave Chinner 提交于 
      Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NBen Myers <bpm@sgi.com>
Signed-off-by: NBen Myers <bpm@sgi.com>
      517c2220
    • D
      xfs: add CRCs to dir2/da node blocks · f5ea1100
      由 Dave Chinner 提交于 
      Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NBen Myers <bpm@sgi.com>
Signed-off-by: NBen Myers <bpm@sgi.com>
      f5ea1100
    • D
      xfs: shortform directory offsets change for dir3 format · 6b2647a1
      由 Dave Chinner 提交于 
      Because the header size for the CRC enabled directory blocks is
larger, the offset of the first entry into a directory block is
different to the dir2 format. The shortform directory stores the
dirent's offset so that it doesn't change when moving from shortform
to block form and back again, and hence it needs to take into
account the different header sizes to maintain the correct offsets.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NBen Myers <bpm@sgi.com>
Signed-off-by: NBen Myers <bpm@sgi.com>
      6b2647a1
    • D
      xfs: add CRC checking to dir2 leaf blocks · 24df33b4
      由 Dave Chinner 提交于 
      This addition follows the same pattern as the dir2 block CRCs.
Seeing as both LEAF1 and LEAFN types need to changed at the same
time, this is a pretty large amount of change. leaf block headers
need to be abstracted away from the on-disk structures (struct
xfs_dir3_icleaf_hdr), as do the base leaf entry locations.

This header abstract allows the in-core header and leaf entry
location to be passed around instead of the leaf block itself. This
saves a lot of converting individual variables from on-disk format
to host format where they are used, so there's a good chance that
the compiler will be able to produce much more optimal code as it's
not having to byteswap variables all over the place.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NBen Myers <bpm@sgi.com>
Signed-off-by: NBen Myers <bpm@sgi.com>
      24df33b4
    • D
      xfs: add CRC checking to dir2 data blocks · 33363fee
      由 Dave Chinner 提交于 
      This addition follows the same pattern as the dir2 block CRCs.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NBen Myers <bpm@sgi.com>
Signed-off-by: NBen Myers <bpm@sgi.com>
      33363fee
    • D
      xfs: add CRC checking to dir2 free blocks · cbc8adf8
      由 Dave Chinner 提交于 
      This addition follows the same pattern as the dir2 block CRCs, but
with a few differences. The main difference is that the free block
header is different between the v2 and v3 formats, so an "in-core"
free block header has been added and _todisk/_from_disk functions
used to abstract the differences in structure format from the code.
This is similar to the on-disk superblock versus the in-core
superblock setup. The in-core strucutre is populated when the buffer
is read from disk, all the in memory checks and modifications are
done on the in-core version of the structure which is written back
to the buffer before the buffer is logged.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NBen Myers <bpm@sgi.com>
Signed-off-by: NBen Myers <bpm@sgi.com>
      cbc8adf8
    • D
      xfs: add CRC checks to block format directory blocks · f5f3d9b0
      由 Dave Chinner 提交于 
      Now that directory buffers are made from a single struct xfs_buf, we
can add CRC calculation and checking callbacks. While there, add all
the fields to the on disk structures for future functionality such
as d_type support, uuids, block numbers, owner inode, etc.

To distinguish between the different on disk formats, change the
magic numbers for the new format directory blocks.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NBen Myers <bpm@sgi.com>
Signed-off-by: NBen Myers <bpm@sgi.com>
      f5f3d9b0
    • D
      xfs: add CRC checks to remote symlinks · f948dd76
      由 Dave Chinner 提交于 
      Add a header to the remote symlink block, containing location and
owner information, as well as CRCs and LSN fields. This requires
verifiers to be added to the remote symlink buffers for CRC enabled
filesystems.

This also fixes a bug reading multiple block symlinks, where the second
block overwrites the first block when copying out the link name.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NBen Myers <bpm@sgi.com>
Signed-off-by: NBen Myers <bpm@sgi.com>
      f948dd76
  3. 22 4月, 2013 8 次提交
  5. 17 4月, 2013 2 次提交
  7. 06 4月, 2013 1 次提交
    • D
      xfs: don't free EFIs before the EFDs are committed · 666d644c
      由 Dave Chinner 提交于 
      Filesystems are occasionally being shut down with this error:

xfs_trans_ail_delete_bulk: attempting to delete a log item that is
not in the AIL.

It was diagnosed to be related to the EFI/EFD commit order when the
EFI and EFD are in different checkpoints and the EFD is committed
before the EFI here:

http://oss.sgi.com/archives/xfs/2013-01/msg00082.html

The real problem is that a single bit cannot fully describe the
states that the EFI/EFD processing can be in. These completion
states are:

EFI			EFI in AIL	EFD		Result
committed/unpinned	Yes		committed	OK
committed/pinned	No		committed	Shutdown
uncommitted		No		committed	Shutdown


Note that the "result" field is what should happen, not what does
happen. The current logic is broken and handles the first two cases
correctly by luck.  That is, the code will free the EFI if the
XFS_EFI_COMMITTED bit is *not* set, rather than if it is set. The
inverted logic "works" because if both EFI and EFD are committed,
then the first __xfs_efi_release() call clears the XFS_EFI_COMMITTED
bit, and the second frees the EFI item. Hence as long as
xfs_efi_item_committed() has been called, everything appears to be
fine.

It is the third case where the logic fails - where
xfs_efd_item_committed() is called before xfs_efi_item_committed(),
and that results in the EFI being freed before it has been
committed. That is the bug that triggered the shutdown, and hence
keeping track of whether the EFI has been committed or not is
insufficient to correctly order the EFI/EFD operations w.r.t. the
AIL.

What we really want is this: the EFI is always placed into the
AIL before the last reference goes away. The only way to guarantee
that is that the EFI is not freed until after it has been unpinned
*and* the EFD has been committed. That is, restructure the logic so
that the only case that can occur is the first case.

This can be done easily by replacing the XFS_EFI_COMMITTED with an
EFI reference count. The EFI is initialised with it's own count, and
that is not released until it is unpinned. However, there is a
complication to this method - the high level EFI/EFD code in
xfs_bmap_finish() does not hold direct references to the EFI
structure, and runs a transaction commit between the EFI and EFD
processing. Hence the EFI can be freed even before the EFD is
created using such a method.

Further, log recovery uses the AIL for tracking EFI/EFDs that need
to be recovered, but it uses the AIL *differently* to the EFI
transaction commit. Hence log recovery never pins or unpins EFIs, so
we can't drop the EFI reference count indirectly to free the EFI.

However, this doesn't prevent us from using a reference count here.
There is a 1:1 relationship between EFIs and EFDs, so when we
initialise the EFI we can take a reference count for the EFD as
well. This solves the xfs_bmap_finish() issue - the EFI will never
be freed until the EFD is processed. In terms of log recovery,
during the committing of the EFD we can look for the
XFS_EFI_RECOVERED bit being set and drop the EFI reference as well,
thereby ensuring everything works correctly there as well.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NMark Tinguely <tinguely@sgi.com>
Signed-off-by: NBen Myers <bpm@sgi.com>
      666d644c
  9. 04 4月, 2013 1 次提交
  11. 23 3月, 2013 7 次提交
  13. 15 3月, 2013 3 次提交
  15. 08 3月, 2013 6 次提交
  17. 04 3月, 2013 2 次提交