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virtiofs: implement FUSE_INIT map_alignment field

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The device communicates FUSE_SETUPMAPPING/FUSE_REMOVMAPPING alignment
constraints via the FUST_INIT map_alignment field.  Parse this field and
ensure our DAX mappings meet the alignment constraints.

We don't actually align anything differently since our mappings are
already 2MB aligned.  Just check the value when the connection is
established.  If it becomes necessary to honor arbitrary alignments in
the future we'll have to adjust how mappings are sized.

The upshot of this commit is that we can be confident that mappings will
work even when emulating x86 on Power and similar combinations where the
host page sizes are different.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Stefan Hajnoczi
2020-08-19 18:19:49 -04:00
committed by Miklos Szeredi
parent 45f2348ece
commit fd1a1dc6f5
4 changed files with 34 additions and 3 deletions
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17
fs/fuse/inode.c
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@@ -908,9 +908,10 @@ static void process_init_reply(struct fuse_conn *fc, struct fuse_args *args,
{
struct fuse_init_args *ia = container_of(args, typeof(*ia), args);
struct fuse_init_out *arg = &ia->out;
bool ok = true;
if (error || arg->major != FUSE_KERNEL_VERSION)
fc->conn_error = 1;
ok = false;
else {
unsigned long ra_pages;
@@ -973,6 +974,11 @@ static void process_init_reply(struct fuse_conn *fc, struct fuse_args *args,
min_t(unsigned int, FUSE_MAX_MAX_PAGES,
max_t(unsigned int, arg->max_pages, 1));
}
if (IS_ENABLED(CONFIG_FUSE_DAX) &&
arg->flags & FUSE_MAP_ALIGNMENT &&
!fuse_dax_check_alignment(fc, arg->map_alignment)) {
ok = false;
}
} else {
ra_pages = fc->max_read / PAGE_SIZE;
fc->no_lock = 1;
@@ -988,6 +994,11 @@ static void process_init_reply(struct fuse_conn *fc, struct fuse_args *args,
}
kfree(ia);
if (!ok) {
fc->conn_init = 0;
fc->conn_error = 1;
}
fuse_set_initialized(fc);
wake_up_all(&fc->blocked_waitq);
}
@@ -1011,6 +1022,10 @@ void fuse_send_init(struct fuse_conn *fc)
FUSE_PARALLEL_DIROPS | FUSE_HANDLE_KILLPRIV | FUSE_POSIX_ACL |
FUSE_ABORT_ERROR | FUSE_MAX_PAGES | FUSE_CACHE_SYMLINKS |
FUSE_NO_OPENDIR_SUPPORT | FUSE_EXPLICIT_INVAL_DATA;
#ifdef CONFIG_FUSE_DAX
if (fc->dax)
ia->in.flags |= FUSE_MAP_ALIGNMENT;
#endif
ia->args.opcode = FUSE_INIT;
ia->args.in_numargs = 1;
ia->args.in_args[0].size = sizeof(ia->in);