Although it was removed in commit 051e7cd44a, ilock needs to be taken in
xfs_readdir because we might have to read the extent list in from disk. This
keeps other threads from reading from or writing to the extent list while it is
being read in and is still in a transitional state.
This has been associated with "Access to block zero" messages on directories
with large numbers of extents resulting from excessive filesytem fragmentation,
as well as extent list corruption. Unfortunately no test case at this point.
Signed-off-by: Ben Myers <bpm@sgi.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Many of the vectorised function calls now take no parameters and
return a constant value. There is no reason for these to be vectored
functions, so convert them to constants
Binary sizes:
text data bss dec hex filename
794490 96802 1096 892388 d9de4 fs/xfs/xfs.o.orig
792986 96802 1096 890884 d9804 fs/xfs/xfs.o.p1
792350 96802 1096 890248 d9588 fs/xfs/xfs.o.p2
789293 96802 1096 887191 d8997 fs/xfs/xfs.o.p3
789005 96802 1096 886903 d8997 fs/xfs/xfs.o.p4
789061 96802 1096 886959 d88af fs/xfs/xfs.o.p5
789733 96802 1096 887631 d8b4f fs/xfs/xfs.o.p6
791421 96802 1096 889319 d91e7 fs/xfs/xfs.o.p7
791701 96802 1096 889599 d92ff fs/xfs/xfs.o.p8
791205 96802 1096 889103 d91cf fs/xfs/xfs.o.p9
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
Convert the rest of the directory data block encode/decode
operations to vector format.
This further reduces the size of the built binary:
text data bss dec hex filename
794490 96802 1096 892388 d9de4 fs/xfs/xfs.o.orig
792986 96802 1096 890884 d9804 fs/xfs/xfs.o.p1
792350 96802 1096 890248 d9588 fs/xfs/xfs.o.p2
789293 96802 1096 887191 d8997 fs/xfs/xfs.o.p3
789005 96802 1096 886903 d8997 fs/xfs/xfs.o.p4
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ben Myers <bpm@sgi.com>
Following from the initial patches to vectorise the shortform
directory encode/decode operations, convert half the data block
operations to use the vector. The rest will be done in a second
patch.
This further reduces the size of the built binary:
text data bss dec hex filename
794490 96802 1096 892388 d9de4 fs/xfs/xfs.o.orig
792986 96802 1096 890884 d9804 fs/xfs/xfs.o.p1
792350 96802 1096 890248 d9588 fs/xfs/xfs.o.p2
789293 96802 1096 887191 d8997 fs/xfs/xfs.o.p3
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ben Myers <bpm@sgi.com>
Following from the initial patch to introduce the directory
operations vector, convert the rest of the shortform directory
operations to use vectored ops rather than superblock feature
checks. This further reduces the size of the built binary:
text data bss dec hex filename
794490 96802 1096 892388 d9de4 fs/xfs/xfs.o.orig
792986 96802 1096 890884 d9804 fs/xfs/xfs.o.p1
792350 96802 1096 890248 d9588 fs/xfs/xfs.o.p2
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ben Myers <bpm@sgi.com>
Lots of the dir code now goes through switches to determine what is
the correct on-disk format to parse. It generally involves a
"xfs_sbversion_hasfoo" check, deferencing the superblock version and
feature fields and hence touching several cache lines per operation
in the process. Some operations do multiple checks because they nest
conditional operations and they don't pass the information in a
direct fashion between each other.
Hence, add an ops vector to the xfs_inode structure that is
configured when the inode is initialised to point to all the correct
decode and encoding operations. This will significantly reduce the
branchiness and cacheline footprint of the directory object decoding
and encoding.
This is the first patch in a series of conversion patches. It will
introduce the ops structure, the setup of it and add the first
operation to the vector. Subsequent patches will convert directory
ops one at a time to keep the changes simple and obvious.
Just this patch shows the benefit of such an approach on code size.
Just converting the two shortform dir operations as this patch does
decreases the built binary size by ~1500 bytes:
$ size fs/xfs/xfs.o.orig fs/xfs/xfs.o.p1
text data bss dec hex filename
794490 96802 1096 892388 d9de4 fs/xfs/xfs.o.orig
792986 96802 1096 890884 d9804 fs/xfs/xfs.o.p1
$
That's a significant decrease in the instruction cache footprint of
the directory code for such a simple change, and indicates that this
approach is definitely worth pursuing further.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ben Myers <bpm@sgi.com>
Currently the xfs_inode.h header has a dependency on the definition
of the BMAP btree records as the inode fork includes an array of
xfs_bmbt_rec_host_t objects in it's definition.
Move all the btree format definitions from xfs_btree.h,
xfs_bmap_btree.h, xfs_alloc_btree.h and xfs_ialloc_btree.h to
xfs_format.h to continue the process of centralising the on-disk
format definitions. With this done, the xfs inode definitions are no
longer dependent on btree header files.
The enables a massive culling of unnecessary includes, with close to
200 #include directives removed from the XFS kernel code base.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
xfs_trans.h has a dependency on xfs_log.h for a couple of
structures. Most code that does transactions doesn't need to know
anything about the log, but this dependency means that they have to
include xfs_log.h. Decouple the xfs_trans.h and xfs_log.h header
files and clean up the includes to be in dependency order.
In doing this, remove the direct include of xfs_trans_reserve.h from
xfs_trans.h so that we remove the dependency between xfs_trans.h and
xfs_mount.h. Hence the xfs_trans.h include can be moved to the
indicate the actual dependencies other header files have on it.
Note that these are kernel only header files, so this does not
translate to any userspace changes at all.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
The on-disk format definitions for the directory and attribute
structures are spread across 3 header files right now, only one of
which is dedicated to defining on-disk structures and their
manipulation (xfs_dir2_format.h). Pull all the format definitions
into a single header file - xfs_da_format.h - and switch all the
code over to point at that.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
The determination of whether a directory entry contains a dtype
field originally was dependent on the filesystem having CRCs
enabled. This meant that the format for dtype beign enabled could be
determined by checking the directory block magic number rather than
doing a feature bit check. This was useful in that it meant that we
didn't need to pass a struct xfs_mount around to functions that
were already supplied with a directory block header.
Unfortunately, the introduction of dtype fields into the v4
structure via a feature bit meant this "use the directory block
magic number" method of discriminating the dirent entry sizes is
broken. Hence we need to convert the places that use magic number
checks to use feature bit checks so that they work correctly and not
by chance.
The current code works on v4 filesystems only because the dirent
size roundup covers the extra byte needed by the dtype field in the
places where this problem occurs.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
Add support for the file type field in directory entries so that
readdir can return the type of the inode the dirent points to to
userspace without first having to read the inode off disk.
The encoding of the type field is a single byte that is added to the
end of the directory entry name length. For all intents and
purposes, it appends a "hidden" byte to the name field which
contains the type information. As the directory entry is already of
dynamic size, helpers are already required to access and decode the
direct entry structures.
Hence the relevent extraction and iteration helpers are updated to
understand the hidden byte. Helpers for reading and writing the
filetype field from the directory entries are also added. Only the
read helpers are used by this patch. It also adds all the code
necessary to read the type information out of the dirents on disk.
Further we add the superblock feature bit and helpers to indicate
that we understand the on-disk format change. This is not a
compatible change - existing kernels cannot read the new format
successfully - so an incompatible feature flag is added. We don't
yet allow filesystems to mount with this flag yet - that will be
added once write support is added.
Finally, the code to take the type from the VFS, convert it to an
XFS on-disk type and put it into the xfs_name structures passed
around is added, but the directory code does not use this field yet.
That will be in the next patch.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
Many of the definitions within xfs_dir2_priv.h are needed in
userspace outside libxfs. Definitions within xfs_dir2_priv.h are
wholly contained within libxfs, so we need to shuffle some of the
definitions around to keep consistency across files shared between
user and kernel space.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
The directory readdir code is not used by userspace, but it is
intermingled with files that are shared with userspace. This makes
it difficult to compare the differences between the userspac eand
kernel files are the userspace files don't have the getdents code in
them. Move all the kernel getdents code to a separate file to bring
the shared content between userspace and kernel files closer
together.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
