Hi, I have been directed here from https://github.com/libfuse/libfuse/issues/488. My issue is that with Linux Kernel 5.4, one read kernel call (e.g. made by cat tool) triggers two fuse_operations.read executions and in both cases with 0 offset even though that first read successfully returned some bytes. For gvfs, it leads to redundant I/O operations, or to "Operation not supported" errors if seeking is not supported. This doesn't happen with Linux 5.3. Any idea what is wrong here? $ strace cat /run/user/1000/gvfs/ftp\:host\=server\,user\=user/foo ... openat(AT_FDCWD, "/run/user/1000/gvfs/ftp:host=server,user=user/foo", O_RDONLY) = 3 fstat(3, {st_mode=S_IFREG|0644, st_size=20, ...}) = 0 fadvise64(3, 0, 0, POSIX_FADV_SEQUENTIAL) = 0 mmap(NULL, 139264, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fbc42b92000 read(3, 0x7fbc42b93000, 131072) = -1 EOPNOTSUPP (Operation not supported) ... $ /usr/libexec/gvfsd-fuse /run/user/1000/gvfs -d ... open flags: 0x8000 /ftp:host=server,user=user/foo open[139679517117488] flags: 0x8000 /ftp:host=server,user=user/foo unique: 8, success, outsize: 32 unique: 10, opcode: READ (15), nodeid: 3, insize: 80, pid: 5053 read[139679517117488] 4096 bytes from 0 flags: 0x8000 read[139679517117488] 20 bytes from 0 unique: 10, success, outsize: 36 unique: 12, opcode: READ (15), nodeid: 3, insize: 80, pid: 5053 read[139679517117488] 4096 bytes from 0 flags: 0x8000 unique: 12, error: -95 (Operation not supported), outsize: 16 ... See for other information: https://gitlab.gnome.org/GNOME/gvfs/issues/441 Regards Ondrej -- Ondrej Holy Software Engineer, Core Desktop Development Red Hat Czech s.r.o
