Commit Graph

153 Commits

Author SHA1 Message Date
Vladimir Sementsov-Ogievskiy
72373e40fb block: bdrv_reopen_multiple: refresh permissions on updated graph
Move bdrv_reopen_multiple to new paradigm of permission update:
first update graph relations, then do refresh the permissions.

We have to modify reopen process in file-posix driver: with new scheme
we don't have prepared permissions in raw_reopen_prepare(), so we
should reconfigure fd in raw_check_perm(). Still this seems more native
and simple anyway.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20210428151804.439460-31-vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2021-04-30 12:27:48 +02:00
Daniel P. Berrangé
8d17adf34f block: remove support for using "file" driver with block/char devices
The 'host_device' and 'host_cdrom' drivers must be used instead.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
2021-03-18 09:22:55 +00:00
Vladimir Sementsov-Ogievskiy
69b55e03f7 block: refactor bdrv_check_request: add errp
It's better to pass &error_abort than just assert that result is 0: on
crash, we'll immediately see the reason in the backtrace.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20201211183934.169161-2-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: fix iotest 206 fallout]
Signed-off-by: Eric Blake <eblake@redhat.com>
2021-02-03 08:00:33 -06:00
David Edmondson
797e3e3805 block: report errno when flock fcntl fails
When a call to fcntl(2) for the purpose of adding file locks fails
with an error other than EAGAIN or EACCES, report the error returned
by fcntl.

EAGAIN or EACCES are elided as they are considered to be common
failures, indicating that a conflicting lock is held by another
process.

No errors are elided when removing file locks.

Signed-off-by: David Edmondson <david.edmondson@oracle.com>
Message-Id: <20210113164447.2545785-1-david.edmondson@oracle.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
2021-01-26 14:36:37 +01:00
Vladimir Sementsov-Ogievskiy
8ac5aab255 block: bdrv_mark_request_serialising: split non-waiting function
We'll need a separate function, which will only "mark" request
serialising with specified align but not wait for conflicting
requests. So, it will be like old bdrv_mark_request_serialising(),
before merging bdrv_wait_serialising_requests_locked() into it.

To reduce the possible mess, let's do the following:

Public function that does both marking and waiting will be called
bdrv_make_request_serialising, and private function which will only
"mark" will be called tracked_request_set_serialising().

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20201021145859.11201-6-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
2020-12-18 12:35:55 +01:00
Pan Nengyuan
cb8d0851f1 block/file-posix: fix a possible undefined behavior
local_err is not initialized to NULL, it will cause a assert error as below:
qemu/util/error.c:59: error_setv: Assertion `*errp == NULL' failed.

Fixes: c644751069
Reported-by: Euler Robot <euler.robot@huawei.com>
Signed-off-by: Pan Nengyuan <pannengyuan@huawei.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Signed-off-by: Chen Qun <kuhn.chenqun@huawei.com>
Message-Id: <20201023061218.2080844-8-kuhn.chenqun@huawei.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
2020-12-13 23:56:16 +01:00
Vladimir Sementsov-Ogievskiy
8b1170012b block: introduce BDRV_MAX_LENGTH
We are going to modify block layer to work with 64bit requests. And
first step is moving to int64_t type for both offset and bytes
arguments in all block request related functions.

It's mostly safe (when widening signed or unsigned int to int64_t), but
switching from uint64_t is questionable.

So, let's first establish the set of requests we want to work with.
First signed int64_t should be enough, as off_t is signed anyway. Then,
obviously offset + bytes should not overflow.

And most interesting: (offset + bytes) being aligned up should not
overflow as well. Aligned to what alignment? First thing that comes in
mind is bs->bl.request_alignment, as we align up request to this
alignment. But there is another thing: look at
bdrv_mark_request_serialising(). It aligns request up to some given
alignment. And this parameter may be bdrv_get_cluster_size(), which is
often a lot greater than bs->bl.request_alignment.
Note also, that bdrv_mark_request_serialising() uses signed int64_t for
calculations. So, actually, we already depend on some restrictions.

Happily, bdrv_get_cluster_size() returns int and
bs->bl.request_alignment has 32bit unsigned type, but defined to be a
power of 2 less than INT_MAX. So, we may establish, that INT_MAX is
absolute maximum for any kind of alignment that may occur with the
request.

Note, that bdrv_get_cluster_size() is not documented to return power
of 2, still bdrv_mark_request_serialising() behaves like it is.
Also, backup uses bdi.cluster_size and is not prepared to it not being
power of 2.
So, let's establish that Qemu supports only power-of-2 clusters and
alignments.

So, alignment can't be greater than 2^30.

Finally to be safe with calculations, to not calculate different
maximums for different nodes (depending on cluster size and
request_alignment), let's simply set QEMU_ALIGN_DOWN(INT64_MAX, 2^30)
as absolute maximum bytes length for Qemu. Actually, it's not much less
than INT64_MAX.

OK, then, let's apply it to block/io.

Let's consider all block/io entry points of offset/bytes:

4 bytes/offset interface functions: bdrv_co_preadv_part(),
bdrv_co_pwritev_part(), bdrv_co_copy_range_internal() and
bdrv_co_pdiscard() and we check them all with bdrv_check_request().

We also have one entry point with only offset: bdrv_co_truncate().
Check the offset.

And one public structure: BdrvTrackedRequest. Happily, it has only
three external users:

 file-posix.c: adopted by this patch
 write-threshold.c: only read fields
 test-write-threshold.c: sets obviously small constant values

Better is to make the structure private and add corresponding
interfaces.. Still it's not obvious what kind of interface is needed
for file-posix.c. Let's keep it public but add corresponding
assertions.

After this patch we'll convert functions in block/io.c to int64_t bytes
and offset parameters. We can assume that offset/bytes pair always
satisfy new restrictions, and make
corresponding assertions where needed. If we reach some offset/bytes
point in block/io.c missing bdrv_check_request() it is considered a
bug. As well, if block/io.c modifies a offset/bytes request, expanding
it more then aligning up to request_alignment, it's a bug too.

For all io requests except for discard we keep for now old restriction
of 32bit request length.

iotest 206 output error message changed, as now test disk size is
larger than new limit. Add one more test case with new maximum disk
size to cover too-big-L1 case.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20201203222713.13507-5-vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-12-11 17:52:40 +01:00
Vladimir Sementsov-Ogievskiy
9b100af30f block/file-posix: fix workaround in raw_do_pwrite_zeroes()
We should not set overlap_bytes:

1. Don't worry: it is calculated by bdrv_mark_request_serialising() and
   will be equal to or greater than bytes anyway.

2. If the request was already aligned up to some greater alignment,
   than we may break things: we reduce overlap_bytes, and further
   bdrv_mark_request_serialising() may not help, as it will not restore
   old bigger alignment.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20201203222713.13507-2-vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-12-11 17:52:40 +01:00
Li Feng
eb43ea16dc file-posix: check the use_lock before setting the file lock
The scenario is that when accessing a volume on an NFS filesystem
without supporting the file lock,  Qemu will complain "Failed to lock
byte 100", even when setting the file.locking = off.

We should do file lock related operations only when the file.locking is
enabled, otherwise, the syscall of 'fcntl' will return non-zero.

Signed-off-by: Li Feng <fengli@smartx.com>
Message-Id: <1607341446-85506-1-git-send-email-fengli@smartx.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-12-11 17:52:40 +01:00
Maxim Levitsky
ece4fa9152 file-posix: allow -EBUSY errors during write zeros on raw block devices
On Linux, fallocate(fd, FALLOC_FL_PUNCH_HOLE) when it is used on a block device,
without O_DIRECT can return -EBUSY if it races with another write to the same page.

Since this is rare and discard is not a critical operation, ignore this error

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20201111153913.41840-2-mlevitsk@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-11-17 12:26:48 +01:00
Daniel P. Berrangé
b18a24a9f8 block/file: switch to use qemu_open/qemu_create for improved errors
Currently at startup if using cache=none on a filesystem lacking
O_DIRECT such as tmpfs, at startup QEMU prints

qemu-system-x86_64: -drive file=/tmp/foo.img,cache=none: file system may not support O_DIRECT
qemu-system-x86_64: -drive file=/tmp/foo.img,cache=none: Could not open '/tmp/foo.img': Invalid argument

while at QMP level the hint is missing, so QEMU reports just

  "error": {
      "class": "GenericError",
      "desc": "Could not open '/tmp/foo.img': Invalid argument"
  }

which is close to useless for the end user trying to figure out what
they did wrong.

With this change at startup QEMU prints

qemu-system-x86_64: -drive file=/tmp/foo.img,cache=none: Unable to open '/tmp/foo.img': filesystem does not support O_DIRECT

while at the QMP level QEMU reports a massively more informative

  "error": {
     "class": "GenericError",
     "desc": "Unable to open '/tmp/foo.img': filesystem does not support O_DIRECT"
  }

Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
2020-09-16 10:33:48 +01:00
Daniel P. Berrangé
448058aa99 util: rename qemu_open() to qemu_open_old()
We want to introduce a new version of qemu_open() that uses an Error
object for reporting problems and make this it the preferred interface.
Rename the existing method to release the namespace for the new impl.

Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
2020-09-16 10:33:48 +01:00
Antoine Damhet
bae127d4dc file-posix: Handle EINVAL fallocate return value
The `detect-zeroes=unmap` option may issue unaligned
`FALLOC_FL_PUNCH_HOLE` requests, raw block devices can (and will) return
`EINVAL`, qemu should then write the zeroes to the blockdev instead of
issuing an `IO_ERROR`.

The problem can be reprodced like this:

$ qemu-io -c 'write -P 0 42 1234' --image-opts driver=host_device,filename=/dev/loop0,detect-zeroes=unmap
write failed: Invalid argument

Signed-off-by: Antoine Damhet <antoine.damhet@blade-group.com>
Message-Id: <20200717135603.51180-1-antoine.damhet@blade-group.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-07-21 16:28:57 +02:00
Kevin Wolf
a8c5cf27c9 file-posix: Fix leaked fd in raw_open_common() error path
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20200717105426.51134-4-kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-07-17 14:20:57 +02:00
Kevin Wolf
bca5283bd4 file-posix: Fix check_hdev_writable() with auto-read-only
For Linux block devices, being able to open the device read-write
doesn't necessarily mean that the device is actually writable (one
example is a read-only LV, as you get with lvchange -pr <device>). We
have check_hdev_writable() to check this condition and fail opening the
image read-write if it's not actually writable.

However, this check doesn't take auto-read-only into account, but
results in a hard failure instead of downgrading to read-only where
possible.

Fix this and do the writable check not based on BDRV_O_RDWR, but only
when this actually results in opening the file read-write. A second
check is inserted in raw_reconfigure_getfd() to have the same check when
dynamic auto-read-only upgrades an image file from read-only to
read-write.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20200717105426.51134-3-kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-07-17 14:20:57 +02:00
Kevin Wolf
20eaf1bf6e file-posix: Move check_hdev_writable() up
We'll need to call it in raw_open_common(), so move the function to
avoid a forward declaration.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20200717105426.51134-2-kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-07-17 14:20:57 +02:00
Kevin Wolf
5edc85571e file-posix: Allow byte-aligned O_DIRECT with NFS
Since commit a6b257a08e ('file-posix: Handle undetectable alignment'),
we assume that if we open a file with O_DIRECT and alignment probing
returns 1, we just couldn't find out the real alignment requirement
because some filesystems make the requirement only for allocated blocks.
In this case, a safe default of 4k is used.

This is too strict for NFS, which does actually allow byte-aligned
requests even with O_DIRECT. Because we can't distinguish both cases
with generic code, let's just look at the file system magic and disable
s->needs_alignment for NFS. This way, O_DIRECT can still be used on NFS
for images that are not aligned to 4k.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200716142601.111237-3-kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-07-17 14:20:57 +02:00
Kevin Wolf
ffa244c84a file-posix: Mitigate file fragmentation with extent size hints
Especially when O_DIRECT is used with image files so that the page cache
indirection can't cause a merge of allocating requests, the file will
fragment on the file system layer, with a potentially very small
fragment size (this depends on the requests the guest sent).

On Linux, fragmentation can be reduced by setting an extent size hint
when creating the file (at least on XFS, it can't be set any more after
the first extent has been allocated), basically giving raw files a
"cluster size" for allocation.

This adds a create option to set the extent size hint, and changes the
default from not setting a hint to setting it to 1 MB. The main reason
why qcow2 defaults to smaller cluster sizes is that COW becomes more
expensive, which is not an issue with raw files, so we can choose a
larger size. The tradeoff here is only potentially wasted disk space.

For qcow2 (or other image formats) over file-posix, the advantage should
even be greater because they grow sequentially without leaving holes, so
there won't be wasted space. Setting even larger extent size hints for
such images may make sense. This can be done with the new option, but
let's keep the default conservative for now.

The effect is very visible with a test that intentionally creates a
badly fragmented file with qemu-img bench (the time difference while
creating the file is already remarkable) and then looks at the number of
extents and the time a simple "qemu-img map" takes.

Without an extent size hint:

    $ ./qemu-img create -f raw -o extent_size_hint=0 ~/tmp/test.raw 10G
    Formatting '/home/kwolf/tmp/test.raw', fmt=raw size=10737418240 extent_size_hint=0
    $ ./qemu-img bench -f raw -t none -n -w ~/tmp/test.raw -c 1000000 -S 8192 -o 0
    Sending 1000000 write requests, 4096 bytes each, 64 in parallel (starting at offset 0, step size 8192)
    Run completed in 25.848 seconds.
    $ ./qemu-img bench -f raw -t none -n -w ~/tmp/test.raw -c 1000000 -S 8192 -o 4096
    Sending 1000000 write requests, 4096 bytes each, 64 in parallel (starting at offset 4096, step size 8192)
    Run completed in 19.616 seconds.
    $ filefrag ~/tmp/test.raw
    /home/kwolf/tmp/test.raw: 2000000 extents found
    $ time ./qemu-img map ~/tmp/test.raw
    Offset          Length          Mapped to       File
    0               0x1e8480000     0               /home/kwolf/tmp/test.raw

    real    0m1,279s
    user    0m0,043s
    sys     0m1,226s

With the new default extent size hint of 1 MB:

    $ ./qemu-img create -f raw -o extent_size_hint=1M ~/tmp/test.raw 10G
    Formatting '/home/kwolf/tmp/test.raw', fmt=raw size=10737418240 extent_size_hint=1048576
    $ ./qemu-img bench -f raw -t none -n -w ~/tmp/test.raw -c 1000000 -S 8192 -o 0
    Sending 1000000 write requests, 4096 bytes each, 64 in parallel (starting at offset 0, step size 8192)
    Run completed in 11.833 seconds.
    $ ./qemu-img bench -f raw -t none -n -w ~/tmp/test.raw -c 1000000 -S 8192 -o 4096
    Sending 1000000 write requests, 4096 bytes each, 64 in parallel (starting at offset 4096, step size 8192)
    Run completed in 10.155 seconds.
    $ filefrag ~/tmp/test.raw
    /home/kwolf/tmp/test.raw: 178 extents found
    $ time ./qemu-img map ~/tmp/test.raw
    Offset          Length          Mapped to       File
    0               0x1e8480000     0               /home/kwolf/tmp/test.raw

    real    0m0,061s
    user    0m0,040s
    sys     0m0,014s

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20200707142329.48303-1-kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-07-14 15:18:59 +02:00
Markus Armbruster
af175e85f9 error: Eliminate error_propagate() with Coccinelle, part 2
When all we do with an Error we receive into a local variable is
propagating to somewhere else, we can just as well receive it there
right away.  The previous commit did that with a Coccinelle script I
consider fairly trustworthy.  This commit uses the same script with
the matching of return taken out, i.e. we convert

    if (!foo(..., &err)) {
        ...
        error_propagate(errp, err);
        ...
    }

to

    if (!foo(..., errp)) {
        ...
        ...
    }

This is unsound: @err could still be read between afterwards.  I don't
know how to express "no read of @err without an intervening write" in
Coccinelle.  Instead, I manually double-checked for uses of @err.

Suboptimal line breaks tweaked manually.  qdev_realize() simplified
further to placate scripts/checkpatch.pl.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200707160613.848843-36-armbru@redhat.com>
2020-07-10 15:18:08 +02:00
Markus Armbruster
668f62ec62 error: Eliminate error_propagate() with Coccinelle, part 1
When all we do with an Error we receive into a local variable is
propagating to somewhere else, we can just as well receive it there
right away.  Convert

    if (!foo(..., &err)) {
        ...
        error_propagate(errp, err);
        ...
        return ...
    }

to

    if (!foo(..., errp)) {
        ...
        ...
        return ...
    }

where nothing else needs @err.  Coccinelle script:

    @rule1 forall@
    identifier fun, err, errp, lbl;
    expression list args, args2;
    binary operator op;
    constant c1, c2;
    symbol false;
    @@
         if (
    (
    -        fun(args, &err, args2)
    +        fun(args, errp, args2)
    |
    -        !fun(args, &err, args2)
    +        !fun(args, errp, args2)
    |
    -        fun(args, &err, args2) op c1
    +        fun(args, errp, args2) op c1
    )
            )
         {
             ... when != err
                 when != lbl:
                 when strict
    -        error_propagate(errp, err);
             ... when != err
    (
             return;
    |
             return c2;
    |
             return false;
    )
         }

    @rule2 forall@
    identifier fun, err, errp, lbl;
    expression list args, args2;
    expression var;
    binary operator op;
    constant c1, c2;
    symbol false;
    @@
    -    var = fun(args, &err, args2);
    +    var = fun(args, errp, args2);
         ... when != err
         if (
    (
             var
    |
             !var
    |
             var op c1
    )
            )
         {
             ... when != err
                 when != lbl:
                 when strict
    -        error_propagate(errp, err);
             ... when != err
    (
             return;
    |
             return c2;
    |
             return false;
    |
             return var;
    )
         }

    @depends on rule1 || rule2@
    identifier err;
    @@
    -    Error *err = NULL;
         ... when != err

Not exactly elegant, I'm afraid.

The "when != lbl:" is necessary to avoid transforming

         if (fun(args, &err)) {
             goto out
         }
         ...
     out:
         error_propagate(errp, err);

even though other paths to label out still need the error_propagate().
For an actual example, see sclp_realize().

Without the "when strict", Coccinelle transforms vfio_msix_setup(),
incorrectly.  I don't know what exactly "when strict" does, only that
it helps here.

The match of return is narrower than what I want, but I can't figure
out how to express "return where the operand doesn't use @err".  For
an example where it's too narrow, see vfio_intx_enable().

Silently fails to convert hw/arm/armsse.c, because Coccinelle gets
confused by ARMSSE being used both as typedef and function-like macro
there.  Converted manually.

Line breaks tidied up manually.  One nested declaration of @local_err
deleted manually.  Preexisting unwanted blank line dropped in
hw/riscv/sifive_e.c.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200707160613.848843-35-armbru@redhat.com>
2020-07-10 15:18:08 +02:00
Markus Armbruster
235e59cf03 qemu-option: Use returned bool to check for failure
The previous commit enables conversion of

    foo(..., &err);
    if (err) {
        ...
    }

to

    if (!foo(..., &err)) {
        ...
    }

for QemuOpts functions that now return true / false on success /
error.  Coccinelle script:

    @@
    identifier fun = {
        opts_do_parse, parse_option_bool, parse_option_number,
        parse_option_size, qemu_opt_parse, qemu_opt_rename, qemu_opt_set,
        qemu_opt_set_bool, qemu_opt_set_number, qemu_opts_absorb_qdict,
        qemu_opts_do_parse, qemu_opts_from_qdict_entry, qemu_opts_set,
        qemu_opts_validate
    };
    expression list args, args2;
    typedef Error;
    Error *err;
    @@
    -    fun(args, &err, args2);
    -    if (err)
    +    if (!fun(args, &err, args2))
         {
             ...
         }

A few line breaks tidied up manually.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20200707160613.848843-15-armbru@redhat.com>
[Conflict with commit 0b6786a9c1 "block/amend: refactor qcow2 amend
options" resolved by rerunning Coccinelle on master's version]
2020-07-10 15:17:35 +02:00
Vladimir Sementsov-Ogievskiy
ac9185603e block/file-posix: drop unallocated_blocks_are_zero
raw_co_block_status() in block/file-posix.c never returns 0, so
unallocated_blocks_are_zero is useless (it doesn't affect the only user
of the field: bdrv_co_block_status()). Drop it.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200528094405.145708-8-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
2020-07-06 10:34:14 +02:00
Eric Blake
47e0b38a13 block: Drop unused .bdrv_has_zero_init_truncate
Now that there are no clients of bdrv_has_zero_init_truncate, none of
the drivers need to worry about providing it.

What's more, this eliminates a source of some confusion: a literal
reading of the documentation as written in ceaca56f and implemented in
commit 1dcaf527 claims that a driver which returns 0 for
bdrv_has_zero_init_truncate() must not return 1 for
bdrv_has_zero_init(); this condition was violated for parallels, qcow,
and sometimes for vdi, although in practice it did not matter since
those drivers also lacked .bdrv_co_truncate.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200428202905.770727-10-eblake@redhat.com>
Acked-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-05-08 13:26:35 +02:00
Simran Singhal
b3ac2b94cd Compress lines for immediate return
Compress two lines into a single line if immediate return statement is found.

It also remove variables progress, val, data, ret and sock
as they are no longer needed.

Remove space between function "mixer_load" and '(' to fix the
checkpatch.pl error:-
ERROR: space prohibited between function name and open parenthesis '('

Done using following coccinelle script:
@@
local idexpression ret;
expression e;
@@

-ret =
+return
     e;
-return ret;

Signed-off-by: Simran Singhal <singhalsimran0@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20200401165314.GA3213@simran-Inspiron-5558>
[lv: in handle_aiocb_write_zeroes_unmap() move "int ret" inside the #ifdef]
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
2020-05-04 14:43:22 +02:00
Kevin Wolf
2f0c6e7a65 file-posix: Support BDRV_REQ_ZERO_WRITE for truncate
For regular files, we always get BDRV_REQ_ZERO_WRITE behaviour from the
OS, so we can advertise the flag and just ignore it.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200424125448.63318-7-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-04-30 17:51:07 +02:00
Kevin Wolf
92b92799dc block: Add flags to BlockDriver.bdrv_co_truncate()
This adds a new BdrvRequestFlags parameter to the .bdrv_co_truncate()
driver callbacks, and a supported_truncate_flags field in
BlockDriverState that allows drivers to advertise support for request
flags in the context of truncate.

For now, we always pass 0 and no drivers declare support for any flag.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200424125448.63318-2-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-04-30 17:51:07 +02:00
Markus Armbruster
77ed971b9d block/file-posix: Fix check_cache_dropped() error handling
The Error ** argument must be NULL, &error_abort, &error_fatal, or a
pointer to a variable containing NULL.  Passing an argument of the
latter kind twice without clearing it in between is wrong: if the
first call sets an error, it no longer points to NULL for the second
call.

check_cache_dropped() calls error_setg() in a loop.  It fails to break
the loop in one instance.  If a subsequent iteration error_setg()s
again, it trips error_setv()'s assertion.

Fix it to break the loop.

Fixes: 31be8a2a97
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200422130719.28225-3-armbru@redhat.com>
2020-04-29 08:01:52 +02:00
Maxim Levitsky
5a5e7f8cd8 block: trickle down the fallback image creation function use to the block drivers
Instead of checking the .bdrv_co_create_opts to see if we need the
fallback, just implement the .bdrv_co_create_opts in the drivers that
need it.

This way we don't break various places that need to know if the
underlying protocol/format really supports image creation, and this way
we still allow some drivers to not support image creation.

Fixes: fd17146cd9
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1816007

Note that technically this driver reverts the image creation fallback
for the vxhs driver since I don't have a means to test it, and IMHO it
is better to leave it not supported as it was prior to generic image
creation patches.

Also drop iscsi_create_opts which was left accidentally.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20200326011218.29230-3-mlevitsk@redhat.com>
Reviewed-by: Denis V. Lunev <den@openvz.org>
[mreitz: Fixed alignment, and moved bdrv_co_create_opts_simple() and
         bdrv_create_opts_simple from block.h into block_int.h]
Signed-off-by: Max Reitz <mreitz@redhat.com>
2020-03-26 14:44:33 +01:00
Maxim Levitsky
b92902dfea block: pass BlockDriver reference to the .bdrv_co_create
This will allow the reuse of a single generic .bdrv_co_create
implementation for several drivers.
No functional changes.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20200326011218.29230-2-mlevitsk@redhat.com>
Reviewed-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Max Reitz <mreitz@redhat.com>
2020-03-26 14:44:33 +01:00
Daniel Henrique Barboza
9bffae14df block: introducing 'bdrv_co_delete_file' interface
Adding to Block Drivers the capability of being able to clean up
its created files can be useful in certain situations. For the
LUKS driver, for instance, a failure in one of its authentication
steps can leave files in the host that weren't there before.

This patch adds the 'bdrv_co_delete_file' interface to block
drivers and add it to the 'file' driver in file-posix.c. The
implementation is given by 'raw_co_delete_file'.

Suggested-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20200130213907.2830642-2-danielhb413@gmail.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-03-11 15:54:38 +01:00
Chen Qun
76e91cda07 block/file-posix: Remove redundant statement in raw_handle_perm_lock()
Clang static code analyzer show warning:
  block/file-posix.c:891:9: warning: Value stored to 'op' is never read
        op = RAW_PL_ABORT;
        ^    ~~~~~~~~~~~~

Reported-by: Euler Robot <euler.robot@huawei.com>
Signed-off-by: Chen Qun <kuhn.chenqun@huawei.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20200302130715.29440-5-kuhn.chenqun@huawei.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
2020-03-09 15:59:31 +01:00
Max Reitz
87ca3b8fa6 file-posix: Drop hdev_co_create_opts()
The generic fallback implementation effectively does the same.

Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200122164532.178040-4-mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
2020-02-20 16:43:42 +01:00
Aarushi Mehta
c644751069 block/file-posix.c: extend to use io_uring
Signed-off-by: Aarushi Mehta <mehta.aaru20@gmail.com>
Reviewed-by: Maxim Levitsky <maximlevitsky@gmail.com>
Acked-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20200120141858.587874-9-stefanha@redhat.com
Message-Id: <20200120141858.587874-9-stefanha@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2020-01-30 20:59:42 +00:00
Paolo Bonzini
18fbd0dec7 block/io: wait for serialising requests when a request becomes serialising
Marking without waiting would not result in actual serialising behavior.
Thus, make a call bdrv_mark_request_serialising sufficient for
serialisation to happen.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1578495356-46219-3-git-send-email-pbonzini@redhat.com
Message-Id: <1578495356-46219-3-git-send-email-pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2020-01-30 20:59:41 +00:00
Markus Armbruster
cb09104ea8 block/file-posix: Fix laio_init() error handling crash bug
raw_aio_attach_aio_context() passes uninitialized Error *local_err by
reference to laio_init() via aio_setup_linux_aio().  When laio_init()
fails, it passes it on to error_setg_errno(), tripping error_setv()'s
assertion unless @local_err is null by dumb luck.

Fix by initializing @local_err properly.

Fixes: ed6e216171
Cc: Nishanth Aravamudan <naravamudan@digitalocean.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20191130194240.10517-4-armbru@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
2019-12-02 16:14:41 +01:00
Max Reitz
292d06b925 block/file-posix: Let post-EOF fallocate serialize
The XFS kernel driver has a bug that may cause data corruption for qcow2
images as of qemu commit c8bb23cbdb.  We can work around it by
treating post-EOF fallocates as serializing up until infinity (INT64_MAX
in practice).

Cc: qemu-stable@nongnu.org
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20191101152510.11719-4-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
2019-11-04 09:33:51 +01:00
Peter Maydell
aaffb85335 Block patches for softfreeze:
- iotest patches
 - Improve performance of the mirror block job in write-blocking mode
 - Limit memory usage for the backup block job
 - Add discard and write-zeroes support to the NVMe host block driver
 - Fix a bug in the mirror job
 - Prevent the qcow2 driver from creating technically non-compliant qcow2
   v3 images (where there is not enough extra data for snapshot table
   entries)
 - Allow callers of bdrv_truncate() (etc.) to determine whether the file
   must be resized to the exact given size or whether it is OK for block
   devices not to shrink
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Merge remote-tracking branch 'remotes/maxreitz/tags/pull-block-2019-10-28' into staging

Block patches for softfreeze:
- iotest patches
- Improve performance of the mirror block job in write-blocking mode
- Limit memory usage for the backup block job
- Add discard and write-zeroes support to the NVMe host block driver
- Fix a bug in the mirror job
- Prevent the qcow2 driver from creating technically non-compliant qcow2
  v3 images (where there is not enough extra data for snapshot table
  entries)
- Allow callers of bdrv_truncate() (etc.) to determine whether the file
  must be resized to the exact given size or whether it is OK for block
  devices not to shrink

# gpg: Signature made Mon 28 Oct 2019 12:13:53 GMT
# gpg:                using RSA key 91BEB60A30DB3E8857D11829F407DB0061D5CF40
# gpg:                issuer "mreitz@redhat.com"
# gpg: Good signature from "Max Reitz <mreitz@redhat.com>" [full]
# Primary key fingerprint: 91BE B60A 30DB 3E88 57D1  1829 F407 DB00 61D5 CF40

* remotes/maxreitz/tags/pull-block-2019-10-28: (69 commits)
  qemu-iotests: restrict 264 to qcow2 only
  Revert "qemu-img: Check post-truncation size"
  block: Pass truncate exact=true where reasonable
  block: Let format drivers pass @exact
  block: Evaluate @exact in protocol drivers
  block: Add @exact parameter to bdrv_co_truncate()
  block: Do not truncate file node when formatting
  block/cor: Drop cor_co_truncate()
  block: Handle filter truncation like native impl.
  iotests: Test qcow2's snapshot table handling
  iotests: Add peek_file* functions
  qcow2: Fix v3 snapshot table entry compliancy
  qcow2: Repair snapshot table with too many entries
  qcow2: Fix overly long snapshot tables
  qcow2: Keep track of the snapshot table length
  qcow2: Fix broken snapshot table entries
  qcow2: Add qcow2_check_fix_snapshot_table()
  qcow2: Separate qcow2_check_read_snapshot_table()
  qcow2: Write v3-compliant snapshot list on upgrade
  qcow2: Put qcow2_upgrade() into its own function
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2019-10-28 14:40:01 +00:00
Max Reitz
82325ae5f2 block: Evaluate @exact in protocol drivers
We have two protocol drivers that return success when trying to shrink a
block device even though they cannot shrink it.  This behavior is now
only allowed with exact=false, so they should return an error with
exact=true.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190918095144.955-6-mreitz@redhat.com
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
2019-10-28 12:05:24 +01:00
Max Reitz
c80d8b06cf block: Add @exact parameter to bdrv_co_truncate()
We have two drivers (iscsi and file-posix) that (in some cases) return
success from their .bdrv_co_truncate() implementation if the block
device is larger than the requested offset, but cannot be shrunk.  Some
callers do not want that behavior, so this patch adds a new parameter
that they can use to turn off that behavior.

This patch just adds the parameter and lets the block/io.c and
block/block-backend.c functions pass it around.  All other callers
always pass false and none of the implementations evaluate it, so that
this patch does not change existing behavior.  Future patches take care
of that.

Suggested-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190918095144.955-5-mreitz@redhat.com
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
2019-10-28 12:00:07 +01:00
Wei Yang
038adc2f58 core: replace getpagesize() with qemu_real_host_page_size
There are three page size in qemu:

  real host page size
  host page size
  target page size

All of them have dedicate variable to represent. For the last two, we
use the same form in the whole qemu project, while for the first one we
use two forms: qemu_real_host_page_size and getpagesize().

qemu_real_host_page_size is defined to be a replacement of
getpagesize(), so let it serve the role.

[Note] Not fully tested for some arch or device.

Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Message-Id: <20191013021145.16011-3-richardw.yang@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2019-10-26 15:38:06 +02:00
Anton Nefedov
d924559953 qapi: query-blockstat: add driver specific file-posix stats
A block driver can provide a callback to report driver-specific
statistics.

file-posix driver now reports discard statistics

Signed-off-by: Anton Nefedov <anton.nefedov@virtuozzo.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Message-id: 20190923121737.83281-10-anton.nefedov@virtuozzo.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
2019-10-10 10:56:18 +02:00
Anton Nefedov
1c45036636 file-posix: account discard operations
This will help to identify how many of the user-issued discard operations
(accounted on a device level) have actually suceeded down on the host file
(even though the numbers will not be exactly the same if non-raw format
driver is used (e.g. qcow2 sending metadata discards)).

Note that these numbers will not include discards triggered by
write-zeroes + MAY_UNMAP calls.

Signed-off-by: Anton Nefedov <anton.nefedov@virtuozzo.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190923121737.83281-9-anton.nefedov@virtuozzo.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
2019-10-10 10:56:18 +02:00
Kevin Wolf
effecce6bc file-posix: Fix has_write_zeroes after NO_FALLBACK
If QEMU_AIO_NO_FALLBACK is given, we always return failure and don't
even try to use the BLKZEROOUT ioctl. In this failure case, we shouldn't
disable has_write_zeroes because we didn't learn anything about the
ioctl. The next request might not set QEMU_AIO_NO_FALLBACK and we can
still use the ioctl then.

Fixes: 738301e117
Reported-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
2019-09-10 08:58:43 +02:00
Max Reitz
b2c6f23f4a block/file-posix: Reduce xfsctl() use
This patch removes xfs_write_zeroes() and xfs_discard().  Both functions
have been added just before the same feature was present through
fallocate():

- fallocate() has supported PUNCH_HOLE for XFS since Linux 2.6.38 (March
  2011); xfs_discard() was added in December 2010.

- fallocate() has supported ZERO_RANGE for XFS since Linux 3.15 (June
  2014); xfs_write_zeroes() was added in November 2013.

Nowadays, all systems that qemu runs on should support both fallocate()
features (RHEL 7's kernel does).

xfsctl() is still useful for getting the request alignment for O_DIRECT,
so this patch does not remove our dependency on it completely.

Note that xfs_write_zeroes() had a bug: It calls ftruncate() when the
file is shorter than the specified range (because ZERO_RANGE does not
increase the file length).  ftruncate() may yield and then discard data
that parallel write requests have written past the EOF in the meantime.
Dropping the function altogether fixes the bug.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Fixes: 50ba5b2d99
Reported-by: Lukáš Doktor <ldoktor@redhat.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Tested-by: Stefano Garzarella <sgarzare@redhat.com>
Tested-by: John Snow <jsnow@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2019-09-10 08:58:43 +02:00
Andrey Shinkevich
294682cc3a block: workaround for unaligned byte range in fallocate()
Revert the commit 118f99442d 'block/io.c: fix for the allocation failure'
and use better error handling for file systems that do not support
fallocate() for an unaligned byte range. Allow falling back to pwrite
in case fallocate() returns EINVAL.

Suggested-by: Kevin Wolf <kwolf@redhat.com>
Suggested-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Denis V. Lunev <den@openvz.org>
Message-Id: <1566913973-15490-1-git-send-email-andrey.shinkevich@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
2019-09-05 16:01:31 -05:00
Stefan Hajnoczi
236094c738 file-posix: fix request_alignment typo
Fixes: a6b257a08e
       ("file-posix: Handle undetectable alignment")
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20190827101328.4062-1-stefanha@redhat.com
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
2019-09-03 14:55:35 +02:00
Nir Soffer
3a20013fbb block: posix: Always allocate the first block
When creating an image with preallocation "off" or "falloc", the first
block of the image is typically not allocated. When using Gluster
storage backed by XFS filesystem, reading this block using direct I/O
succeeds regardless of request length, fooling alignment detection.

In this case we fallback to a safe value (4096) instead of the optimal
value (512), which may lead to unneeded data copying when aligning
requests.  Allocating the first block avoids the fallback.

Since we allocate the first block even with preallocation=off, we no
longer create images with zero disk size:

    $ ./qemu-img create -f raw test.raw 1g
    Formatting 'test.raw', fmt=raw size=1073741824

    $ ls -lhs test.raw
    4.0K -rw-r--r--. 1 nsoffer nsoffer 1.0G Aug 16 23:48 test.raw

And converting the image requires additional cluster:

    $ ./qemu-img measure -f raw -O qcow2 test.raw
    required size: 458752
    fully allocated size: 1074135040

When using format like vmdk with multiple files per image, we allocate
one block per file:

    $ ./qemu-img create -f vmdk -o subformat=twoGbMaxExtentFlat test.vmdk 4g
    Formatting 'test.vmdk', fmt=vmdk size=4294967296 compat6=off hwversion=undefined subformat=twoGbMaxExtentFlat

    $ ls -lhs test*.vmdk
    4.0K -rw-r--r--. 1 nsoffer nsoffer 2.0G Aug 27 03:23 test-f001.vmdk
    4.0K -rw-r--r--. 1 nsoffer nsoffer 2.0G Aug 27 03:23 test-f002.vmdk
    4.0K -rw-r--r--. 1 nsoffer nsoffer  353 Aug 27 03:23 test.vmdk

I did quick performance test for copying disks with qemu-img convert to
new raw target image to Gluster storage with sector size of 512 bytes:

    for i in $(seq 10); do
        rm -f dst.raw
        sleep 10
        time ./qemu-img convert -f raw -O raw -t none -T none src.raw dst.raw
    done

Here is a table comparing the total time spent:

Type    Before(s)   After(s)    Diff(%)
---------------------------------------
real      530.028    469.123      -11.4
user       17.204     10.768      -37.4
sys        17.881      7.011      -60.7

We can see very clear improvement in CPU usage.

Signed-off-by: Nir Soffer <nsoffer@redhat.com>
Message-id: 20190827010528.8818-2-nsoffer@redhat.com
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
2019-09-03 14:55:35 +02:00
Max Reitz
1dcaf52760 block: Implement .bdrv_has_zero_init_truncate()
We need to implement .bdrv_has_zero_init_truncate() for every block
driver that supports truncation and has a .bdrv_has_zero_init()
implementation.

Implement it the same way each driver implements .bdrv_has_zero_init().
This is at least not any more unsafe than what we had before.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190724171239.8764-5-mreitz@redhat.com
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
2019-08-19 17:13:26 +02:00
Paolo Bonzini
f6fc1e30cf block: fix NetBSD qemu-iotests failure
Opening a block device on NetBSD has an additional step compared to other OSes,
corresponding to raw_normalize_devicepath.  The error message in that function
is slightly different from that in raw_open_common and this was causing spurious
failures in qemu-iotests.  However, in general it is not important to know what
exact step was failing, for example in the qemu-iotests case the error message
contains the fairly unequivocal "No such file or directory" text from strerror.
We can thus fix the failures by standardizing on a single error message for
both raw_open_common and raw_normalize_devicepath; in fact, we can even
use error_setg_file_open to make sure the error message is the same as in
the rest of QEMU.

Message-Id: <20190725095920.28419-1-pbonzini@redhat.com>
Tested-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
2019-08-17 09:02:59 +02:00
Nir Soffer
a6b257a08e file-posix: Handle undetectable alignment
In some cases buf_align or request_alignment cannot be detected:

1. With Gluster, buf_align cannot be detected since the actual I/O is
   done on Gluster server, and qemu buffer alignment does not matter.
   Since we don't have alignment requirement, buf_align=1 is the best
   value.

2. With local XFS filesystem, buf_align cannot be detected if reading
   from unallocated area. In this we must align the buffer, but we don't
   know what is the correct size. Using the wrong alignment results in
   I/O error.

3. With Gluster backed by XFS, request_alignment cannot be detected if
   reading from unallocated area. In this case we need to use the
   correct alignment, and failing to do so results in I/O errors.

4. With NFS, the server does not use direct I/O, so both buf_align cannot
   be detected. In this case we don't need any alignment so we can use
   buf_align=1 and request_alignment=1.

These cases seems to work when storage sector size is 512 bytes, because
the current code starts checking align=512. If the check succeeds
because alignment cannot be detected we use 512. But this does not work
for storage with 4k sector size.

To determine if we can detect the alignment, we probe first with
align=1. If probing succeeds, maybe there are no alignment requirement
(cases 1, 4) or we are probing unallocated area (cases 2, 3). Since we
don't have any way to tell, we treat this as undetectable alignment. If
probing with align=1 fails with EINVAL, but probing with one of the
expected alignments succeeds, we know that we found a working alignment.

Practically the alignment requirements are the same for buffer
alignment, buffer length, and offset in file. So in case we cannot
detect buf_align, we can use request alignment. If we cannot detect
request alignment, we can fallback to a safe value. To use this logic,
we probe first request alignment instead of buf_align.

Here is a table showing the behaviour with current code (the value in
parenthesis is the optimal value).

Case    Sector    buf_align (opt)   request_alignment (opt)     result
======================================================================
1       512       512   (1)          512   (512)                 OK
1       4096      512   (1)          4096  (4096)                FAIL
----------------------------------------------------------------------
2       512       512   (512)        512   (512)                 OK
2       4096      512   (4096)       4096  (4096)                FAIL
----------------------------------------------------------------------
3       512       512   (1)          512   (512)                 OK
3       4096      512   (1)          512   (4096)                FAIL
----------------------------------------------------------------------
4       512       512   (1)          512   (1)                   OK
4       4096      512   (1)          512   (1)                   OK

Same cases with this change:

Case    Sector    buf_align (opt)   request_alignment (opt)     result
======================================================================
1       512       512   (1)          512   (512)                 OK
1       4096      4096  (1)          4096  (4096)                OK
----------------------------------------------------------------------
2       512       512   (512)        512   (512)                 OK
2       4096      4096  (4096)       4096  (4096)                OK
----------------------------------------------------------------------
3       512       4096  (1)          4096  (512)                 OK
3       4096      4096  (1)          4096  (4096)                OK
----------------------------------------------------------------------
4       512       4096  (1)          4096  (1)                   OK
4       4096      4096  (1)          4096  (1)                   OK

I tested that provisioning VMs and copying disks on local XFS and
Gluster with 4k bytes sector size work now, resolving bugs [1],[2].
I tested also on XFS, NFS, Gluster with 512 bytes sector size.

[1] https://bugzilla.redhat.com/1737256
[2] https://bugzilla.redhat.com/1738657

Signed-off-by: Nir Soffer <nsoffer@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2019-08-16 11:29:11 +02:00