rq->data_len served two purposes - the length of data buffer on issue
and the residual count on completion. This duality creates some
headaches.
First of all, block layer and low level drivers can't really determine
what rq->data_len contains while a request is executing. It could be
the total request length or it coulde be anything else one of the
lower layers is using to keep track of residual count. This
complicates things because blk_rq_bytes() and thus
[__]blk_end_request_all() relies on rq->data_len for PC commands.
Drivers which want to report residual count should first cache the
total request length, update rq->data_len and then complete the
request with the cached data length.
Secondly, it makes requests default to reporting full residual count,
ie. reporting that no data transfer occurred. The residual count is
an exception not the norm; however, the driver should clear
rq->data_len to zero to signify the normal cases while leaving it
alone means no data transfer occurred at all. This reverse default
behavior complicates code unnecessarily and renders block PC on some
drivers (ide-tape/floppy) unuseable.
This patch adds rq->resid_len which is used only for residual count.
While at it, remove now unnecessasry blk_rq_bytes() caching in
ide_pc_intr() as rq->data_len is not changed anymore.
Boaz : spotted missing conversion in osd
Sergei : spotted too early conversion to blk_rq_bytes() in ide-tape
[ Impact: cleanup residual count handling, report 0 resid by default ]
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Cc: Borislav Petkov <petkovbb@googlemail.com>
Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: Mike Miller <mike.miller@hp.com>
Cc: Eric Moore <Eric.Moore@lsi.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Doug Gilbert <dgilbert@interlog.com>
Cc: Mike Miller <mike.miller@hp.com>
Cc: Eric Moore <Eric.Moore@lsi.com>
Cc: Darrick J. Wong <djwong@us.ibm.com>
Cc: Pete Zaitcev <zaitcev@redhat.com>
Cc: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Added some documentation in exofs.txt, as well as a BUGS file.
For further reading, operation instructions, example scripts
and up to date infomation and code please see:
http://open-osd.org
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
This patch ties all operation vectors into a file system superblock
and registers the exofs file_system_type at module's load time.
* The file system control block (AKA on-disk superblock) resides in
an object with a special ID (defined in common.h).
Information included in the file system control block is used to
fill the in-memory superblock structure at mount time. This object
is created before the file system is used by mkexofs.c It contains
information such as:
- The file system's magic number
- The next inode number to be allocated
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
implementation of directory and inode operations.
* A directory is treated as a file, and essentially contains a list
of <file name, inode #> pairs for files that are found in that
directory. The object IDs correspond to the files' inode numbers
and are allocated using a 64bit incrementing global counter.
* Each file's control block (AKA on-disk inode) is stored in its
object's attributes. This applies to both regular files and other
types (directories, device files, symlinks, etc.).
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
OK Now we start to read and write from osd-objects. We try to
collect at most contiguous pages as possible in a single write/read.
The first page index is the object's offset.
TODO:
In 64-bit a single bio can carry at most 128 pages.
Add support of chaining multiple bios
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
implementation of the file_operations and inode_operations for
regular data files.
Most file_operations are generic vfs implementations except:
- exofs_truncate will truncate the OSD object as well
- Generic file_fsync is not good for none_bd devices so open code it
- The default for .flush in Linux is todo nothing so call exofs_fsync
on the file.
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
This patch includes osd infrastructure that will be used later by
the file system.
Also the declarations of constants, on disk structures,
and prototypes.
And the Kbuild+Kconfig files needed to build the exofs module.
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
