This patch adds back O_DIRECT support with various caveats
attached:
1. Journaled data can be read via O_DIRECT since its now the
same on disk format as normal data files.
2. Journaled data writes with O_DIRECT will be failed sliently
back to normal writes (should we really do this I wonder or
should we return an error instead?)
3. Stuffed files will be failed back to normal buffered I/O
4. All the usual corner cases (write beyond current end of file,
write to an unallocated block) will also revert to normal buffered I/O.
The I/O path is slightly odd as reads arrive at the page cache layer
with the lock for the file already held, but writes arrive unlocked.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This is a very large patch, with a few still to be resolved issues
so you might want to check out the previous head of the tree since
this is known to be unstable. Fixes for the various bugs will be
forthcoming shortly.
This patch removes the special data format which has been used
up till now for journaled data files. Directories still retain the
old format so that they will remain on disk compatible with earlier
releases. As a result you can now do the following with journaled
data files:
1) mmap them
2) export them over NFS
3) convert to/from normal files whenever you want to (the zero length
restriction is gone)
In addition the level at which GFS' locking is done has changed for all
files (since they all now use the page cache) such that the locking is
done at the page cache level rather than the level of the fs operations.
This should mean that things like loopback mounts and other things which
touch the page cache directly should now work.
Current known issues:
1. There is a lock mode inversion problem related to the resource
group hold function which needs to be resolved.
2. Any significant amount of I/O causes an oops with an offset of hex 320
(NULL pointer dereference) which appears to be related to a journaled data
buffer appearing on a list where it shouldn't be.
3. Direct I/O writes are disabled for the time being (will reappear later)
4. There is probably a deadlock between the page lock and GFS' locks under
certain combinations of mmap and fs operation I/O.
5. Issue relating to ref counting on internally used inodes causes a hang
on umount (discovered before this patch, and not fixed by it)
6. One part of the directory metadata is different from GFS1 and will need
to be resolved before next release.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Update the function in GFS2 which deals with truncation of
partial blocks. Some of the code is "borrowed" from ext3
since it appears to give a good model of how to do this
operation. The function is renamed gfs2_block_truncate_page
accordingly.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Removing the gfs2_databuf structure and using gfs2_bufdata instead
is a step towards allowing journaling of data without requiring the
metadata header on each journaled block. The idea is to merge the
code paths for ordered data with that of journaled data, with the
log operations in lops.c tacking account of the different types of
buffers as they are presented to it. Largely the code path for
metadata will be similar too, but obviously through a different set
of log operations.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This adds an extra argument to gfs2_trans_add_bh() to indicate whether the
bh being added to the transaction is metadata or data. Its currently unused
since all existing callers set it to 1 (metadata) but following patches will
make use of it.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This patch contains all the core files for GFS2.
Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
