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| author |   Richard W.M. Jones <rjones@redhat.com> | 2021-05-12 17:18:48 +0100 |
|---|---|---|
| committer |   Miklos Szeredi <mszeredi@redhat.com> | 2021-06-22 09:15:36 +0200 |
| commit | 6b1bdb56b17c25f640261f3b18030cb0a21d7878 (patch) | |
| tree | 189d4777fac7cbce17e8acad2c6409ad0b5af326 /fs/fuse | |
| parent | fuse: Make fuse_fill_super_submount() static (diff) | |
| download | linux-dev-6b1bdb56b17c25f640261f3b18030cb0a21d7878.tar.xz linux-dev-6b1bdb56b17c25f640261f3b18030cb0a21d7878.zip | |
fuse: allow fallocate(FALLOC_FL_ZERO_RANGE)
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 <rjones@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs/fuse')
| -rw-r--r-- | fs/fuse/file.c | 10 |
1 files 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); |