v3 -> v4:
- Cleans up the commit message.
- As the patch itself is unchanged from v3, I did not retest it.
The current fuse module filters out fallocate(FALLOC_FL_ZERO_RANGE)
returning -EOPNOTSUPP. libnbd's nbdfuse would like to translate
FALLOC_FL_ZERO_RANGE requests into the NBD command
NBD_CMD_WRITE_ZEROES which allows NBD servers that support it to do
zeroing efficiently.
This commit treats this flag exactly like FALLOC_FL_PUNCH_HOLE.
A way to test this, requiring fuse >= 3, nbdkit >= 1.8 and the latest
nbdfuse from https://gitlab.com/nbdkit/libnbd/-/tree/master/fuse is to
create a file containing some data and "mirror" it to a fuse file:
$ dd if=/dev/urandom of=disk.img bs=1M count=1
$ nbdkit file disk.img
$ touch mirror.img
$ nbdfuse mirror.img nbd://localhost &
(mirror.img -> nbdfuse -> NBD over loopback -> nbdkit -> disk.img)
You can then run commands such as:
$ fallocate -z -o 1024 -l 1024 mirror.img
and check that the content of the original file ("disk.img") stays
synchronized. To show NBD commands, export LIBNBD_DEBUG=1 before
running nbdfuse. To clean up:
$ fusermount3 -u mirror.img
$ killall nbdkit
Signed-off-by: Richard W.M. Jones <[email protected]>
---
fs/fuse/file.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 09ef2a4d25ed..ec20a1801c1b 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -2907,11 +2907,13 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
};
int err;
bool lock_inode = !(mode & FALLOC_FL_KEEP_SIZE) ||
- (mode & FALLOC_FL_PUNCH_HOLE);
+ (mode & (FALLOC_FL_PUNCH_HOLE |
+ FALLOC_FL_ZERO_RANGE));
bool block_faults = FUSE_IS_DAX(inode) && lock_inode;
- if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
+ if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |
+ FALLOC_FL_ZERO_RANGE))
return -EOPNOTSUPP;
if (fm->fc->no_fallocate)
@@ -2926,7 +2928,7 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
goto out;
}
- if (mode & FALLOC_FL_PUNCH_HOLE) {
+ if (mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) {
loff_t endbyte = offset + length - 1;
err = fuse_writeback_range(inode, offset, endbyte);
@@ -2966,7 +2968,7 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset,
file_update_time(file);
}
- if (mode & FALLOC_FL_PUNCH_HOLE)
+ if (mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE))
truncate_pagecache_range(inode, offset, offset + length - 1);
fuse_invalidate_attr(inode);
--
2.31.1
On Wed, 12 May 2021 at 18:19, Richard W.M. Jones <[email protected]> wrote:
>
> The current fuse module filters out fallocate(FALLOC_FL_ZERO_RANGE)
> returning -EOPNOTSUPP. libnbd's nbdfuse would like to translate
> FALLOC_FL_ZERO_RANGE requests into the NBD command
> NBD_CMD_WRITE_ZEROES which allows NBD servers that support it to do
> zeroing efficiently.
>
> This commit treats this flag exactly like FALLOC_FL_PUNCH_HOLE.
Thanks, applied.
Miklos
On Tue, May 18, 2021 at 03:56:25PM +0200, Miklos Szeredi wrote:
> On Wed, 12 May 2021 at 18:19, Richard W.M. Jones <[email protected]> wrote:
> >
> > The current fuse module filters out fallocate(FALLOC_FL_ZERO_RANGE)
> > returning -EOPNOTSUPP. libnbd's nbdfuse would like to translate
> > FALLOC_FL_ZERO_RANGE requests into the NBD command
> > NBD_CMD_WRITE_ZEROES which allows NBD servers that support it to do
> > zeroing efficiently.
> >
> > This commit treats this flag exactly like FALLOC_FL_PUNCH_HOLE.
>
> Thanks, applied.
Hi Miklos, did this patch get forgotten?
Rich.
--
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Read my programming and virtualization blog: http://rwmj.wordpress.com
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On Tue, 15 Jun 2021 at 12:34, Richard W.M. Jones <[email protected]> wrote:
>
> On Tue, May 18, 2021 at 03:56:25PM +0200, Miklos Szeredi wrote:
> > On Wed, 12 May 2021 at 18:19, Richard W.M. Jones <[email protected]> wrote:
> > >
> > > The current fuse module filters out fallocate(FALLOC_FL_ZERO_RANGE)
> > > returning -EOPNOTSUPP. libnbd's nbdfuse would like to translate
> > > FALLOC_FL_ZERO_RANGE requests into the NBD command
> > > NBD_CMD_WRITE_ZEROES which allows NBD servers that support it to do
> > > zeroing efficiently.
> > >
> > > This commit treats this flag exactly like FALLOC_FL_PUNCH_HOLE.
> >
> > Thanks, applied.
>
> Hi Miklos, did this patch get forgotten?
It's in my internal patch queue. Will push to fuse.git#for-next in a few days.
Thanks,
Miklos