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authorRichard W.M. Jones <rjones@redhat.com>2021-05-12 17:18:48 +0100
committerMiklos Szeredi <mszeredi@redhat.com>2021-06-22 09:15:36 +0200
commit6b1bdb56b17c25f640261f3b18030cb0a21d7878 (patch)
tree189d4777fac7cbce17e8acad2c6409ad0b5af326 /fs/fuse
parent1b539917374d26fb64395eeb5d4baebd7ad38f61 (diff)
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.c10
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);