If an object is referenced by a directory but does not
exist on a target, it is a very serious corruption that
means:
1. Either a power failure with very slim chance of it
happening. Because the directory update is always submitted
much after object creation, but if a directory is written
to one device and the object creation to another it might
theoretically happen.
2. It only ever happened to me while developing with BUGs
causing file corruption. Crashes could also cause it but
they are more like case 1.
In any way the object does not exist, so data is surely lost.
If there is a mix-up in the obj-id or data-map, then lost objects
can be salvaged by off-line fsck. The only recoverable information
is the directory name. By letting it appear as a regular empty file,
with date==0 (1970 Jan 1st) ownership to root, we enable recovery
of the only useful information. And also enable deletion or over-write.
I can see how this can hurt.
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
* inode.c operations are full-pages based, and not actually
true scatter-gather
* Lets us use more pages at once upto 512 (from 249) in 64 bit
* Brings us much much closer to be able to use exofs's io_state engine
from objlayout driver. (Once I decide where to put the common code)
After RAID0 patch the outer (input) bio was never used as a bio, but
was simply a page carrier into the raid engine. Even in the simple
mirror/single-dev arrangement pages info was copied into a second bio.
It is now easer to just pass a pages array into the io_state and prepare
bio(s) once.
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
We now support striping over mirror devices. Including variable sized
stripe_unit.
Some limits:
* stripe_unit must be a multiple of PAGE_SIZE
* stripe_unit * stripe_count is maximum upto 32-bit (4Gb)
Tested RAID0 over mirrors, RAID0 only, mirrors only. All check.
Design notes:
* I'm not using a vectored raid-engine mechanism yet. Following the
pnfs-objects-layout data-map structure, "Mirror" is just a private
case of "group_width" == 1, and RAID0 is a private case of
"Mirrors" == 1. The performance lose of the general case over the
particular special case optimization is totally negligible, also
considering the extra code size.
* In general I added a prepare_stripes() stage that divides the
to-be-io pages to the participating devices, the previous
exofs_ios_write/read, now becomes _write/read_mirrors and a new
write/read upper layer loops on all devices calling
_write/read_mirrors. Effectively the prepare_stripes stage is the all
secret.
Also truncate need fixing to accommodate for striping.
* In a RAID0 arrangement, in a regular usage scenario, if all inode
layouts will start at the same device, the small files fill up the
first device and the later devices stay empty, the farther the device
the emptier it is.
To fix that, each inode will start at a different stripe_unit,
according to it's obj_id modulus number-of-stripe-units. And
will then span all stripe-units in the same incrementing order
wrapping back to the beginning of the device table. We call it
a stripe-units moving window.
Special consideration was taken to keep all devices in a mirror
arrangement identical. So a broken osd-device could just be cloned
from one of the mirrors and no FS scrubbing is needed. (We do that
by rotating stripe-unit at a time and not a single device at a time.)
TODO:
We no longer verify object_length == inode->i_size in exofs_iget.
(since i_size is stripped on multiple objects now).
I should introduce a multiple-device attribute reading, and use
it in exofs_iget.
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
* Layouts describe the way a file is spread on multiple devices.
The layout information is stored in the objects attribute introduced
in this patch.
* There can be multiple generating function for the layout.
Currently defined:
- No attribute present - use below moving-window on global
device table, all devices.
(This is the only one currently used in exofs)
- an obj_id generated moving window - the obj_id is a randomizing
factor in the otherwise global map layout.
- An explicit layout stored, including a data_map and a device
index list.
- More might be defined in future ...
* There are two attributes defined of the same structure:
A-data-files-layout - This layout is used by data-files. If present
at a directory, all files of that directory will
be created with this layout.
A-meta-data-layout - This layout is used by a directory and other
meta-data information. Also inherited at creation
of subdirectories.
* At creation time inodes are created with the layout specified above.
A usermode utility may change the creation layout on a give directory
or file. Which in the case of directories, will also apply to newly
created files/subdirectories, children of that directory.
In the simple unaltered case of a newly created exofs, no layout
attributes are present, and all layouts adhere to the layout specified
at the device-table.
* In case of a future file system loaded in an old exofs-driver.
At iget(), the generating_function is inspected and if not supported
will return an IO error to the application and the inode will not
be loaded. So not to damage any data.
Note: After this patch we do not yet support any type of layout
only the RAID0 patch that enables striping at the super-block
level will add support for RAID0 layouts above. This way we
are past and future compatible and fully bisectable.
* Access to the device table is done by an accessor since
it will change according to above information.
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
* Abstract away those members in exofs_sb_info that are related/needed
by a layout into a new exofs_layout structure. Embed it in exofs_sb_info.
* At exofs_io_state receive/keep a pointer to an exofs_layout. No need for
an exofs_sb_info pointer, all we need is at exofs_layout.
* Change any usage of above exofs_sb_info members to their new name.
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
* Last debug trimming left in some stupid print, remove them.
Fixup some other prints
* Shift printing from inode.c to ios.c
* Add couple of prints when memory allocation fails.
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
exofs uses simple_write_end() for it's .write_end handler. But
it is not enough because simple_write_end() does not call
mark_inode_dirty() when it extends i_size. So even if we do
call mark_inode_dirty at beginning of write out, with a very
long IO and a saturated system we might get the .write_inode()
called while still extend-writing to file and miss out on the last
i_size updates.
So override .write_end, call simple_write_end(), and afterwords if
i_size was changed call mark_inode_dirty().
It stands to logic that since simple_write_end() was the one extending
i_size it should also call mark_inode_dirty(). But it looks like all
users of simple_write_end() are memory-bound pseudo filesystems, who
could careless about mark_inode_dirty(). I might submit a
warning-comment patch to simple_write_end() in future.
CC: Stable <stable@kernel.org>
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
This patch changes on-disk format, it is accompanied with a parallel
patch to mkfs.exofs that enables multi-device capabilities.
After this patch, old exofs will refuse to mount a new formatted FS and
new exofs will refuse an old format. This is done by moving the magic
field offset inside the FSCB. A new FSCB *version* field was added. In
the future, exofs will refuse to mount unmatched FSCB version. To
up-grade or down-grade an exofs one must use mkfs.exofs --upgrade option
before mounting.
Introduced, a new object that contains a *device-table*. This object
contains the default *data-map* and a linear array of devices
information, which identifies the devices used in the filesystem. This
object is only written to offline by mkfs.exofs. This is why it is kept
separate from the FSCB, since the later is written to while mounted.
Same partition number, same object number is used on all devices only
the device varies.
* define the new format, then load the device table on mount time make
sure every thing is supported.
* Change I/O engine to now support Mirror IO, .i.e write same data
to multiple devices, read from a random device to spread the
read-load from multiple clients (TODO: stripe read)
Implementation notes:
A few points introduced in previous patch should be mentioned here:
* Special care was made so absolutlly all operation that have any chance
of failing are done before any osd-request is executed. This is to
minimize the need for a data consistency recovery, to only real IO
errors.
* Each IO state has a kref. It starts at 1, any osd-request executed
will increment the kref, finally when all are executed the first ref
is dropped. At IO-done, each request completion decrements the kref,
the last one to return executes the internal _last_io() routine.
_last_io() will call the registered io_state_done. On sync mode a
caller does not supply a done method, indicating a synchronous
request, the caller is put to sleep and a special io_state_done is
registered that will awaken the caller. Though also in sync mode all
operations are executed in parallel.
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
In anticipation for multi-device operations, we separate osd operations
into an abstract I/O API. Currently only one device is used but later
when adding more devices, we will drive all devices in parallel according
to a "data_map" that describes how data is arranged on multiple devices.
The file system level operates, like before, as if there is one object
(inode-number) and an i_size. The io engine will split this to the same
object-number but on multiple device.
At first we introduce Mirror (raid 1) layout. But at the final outcome
we intend to fully implement the pNFS-Objects data-map, including
raid 0,4,5,6 over mirrored devices, over multiple device-groups. And
more. See: http://tools.ietf.org/html/draft-ietf-nfsv4-pnfs-obj-12
* Define an io_state based API for accessing osd storage devices
in an abstract way.
Usage:
First a caller allocates an io state with:
exofs_get_io_state(struct exofs_sb_info *sbi,
struct exofs_io_state** ios);
Then calles one of:
exofs_sbi_create(struct exofs_io_state *ios);
exofs_sbi_remove(struct exofs_io_state *ios);
exofs_sbi_write(struct exofs_io_state *ios);
exofs_sbi_read(struct exofs_io_state *ios);
exofs_oi_truncate(struct exofs_i_info *oi, u64 new_len);
And when done
exofs_put_io_state(struct exofs_io_state *ios);
* Convert all source files to use this new API
* Convert from bio_alloc to bio_kmalloc
* In io engine we make use of the now fixed osd_req_decode_sense
There are no functional changes or on disk additions after this patch.
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
There are two places that initialize inodes: exofs_iget() and
exofs_new_inode()
As more members of exofs_i_info that need initialization are
added this code will grow. (soon)
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Iner-loops printing is converted to EXOFS_DBG2 which is #defined
to nothing.
It is now almost bareable to just leave debug-on. Every operation
is printed once, with most relevant info (I hope).
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Boaz,
Congrats on getting all the OSD stuff into 2.6.30!
I just pulled the git, and saw that the IBM copyrights are still there.
Please remove them from all files:
* Copyright (C) 2005, 2006
* International Business Machines
IBM has revoked all rights on the code - they gave it to me.
Thanks!
Avishay
Signed-off-by: Avishay Traeger <avishay@gmail.com>
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
When failing a read request in the sync path, called from
write_begin, I forgot to free the allocated bio, fix it.
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
libosd users that need to work with bios, must sometime use
the request_queue associated with the osd_dev. Make a wrapper for
that, and convert all in-tree users.
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
For supporting of chained-bios we can not inspect the first
bio only, as before. Caller shall pass the total length of the
request, ie. sum_bytes(bio-chain).
Also since the bio might be a chain we don't set it's direction
on behalf of it's callers. The bio direction should be properly
set prior to this call. So fix a couple of write users that now
need to set the bio direction properly
[In this patch I change both library code and user sites at
exofs, to make it easy on integration. It should be submitted
via James's scsi-misc tree.]
Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
CC: Jeff Garzik <jeff@garzik.org>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.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>
