On 11/14/24 21:57, Joanne Koong wrote:
> On Thu, Nov 7, 2024 at 9:04 AM Bernd Schubert <bschubert@xxxxxxx> wrote:
>>
>> This change sets up FUSE operations to have headers in args.in_args[0],
>> even for opcodes without an actual header. We do this to prepare for
>> cleanly separating payload from headers in the future.
>>
>> For opcodes without a header, we use a zero-sized struct as a
>> placeholder. This approach:
>> - Keeps things consistent across all FUSE operations
>> - Will help with payload alignment later
>> - Avoids future issues when header sizes change
>>
>> Signed-off-by: Bernd Schubert <bschubert@xxxxxxx>
>> ---
>> fs/fuse/dax.c | 13 ++++++++-----
>> fs/fuse/dev.c | 24 ++++++++++++++++++++----
>> fs/fuse/dir.c | 41 +++++++++++++++++++++++++++--------------
>> fs/fuse/fuse_i.h | 7 +++++++
>> fs/fuse/xattr.c | 9 ++++++---
>> 5 files changed, 68 insertions(+), 26 deletions(-)
>>
>> diff --git a/fs/fuse/dax.c b/fs/fuse/dax.c
>> index 12ef91d170bb3091ac35a33d2b9dc38330b00948..e459b8134ccb089f971bebf8da1f7fc5199c1271 100644
>> --- a/fs/fuse/dax.c
>> +++ b/fs/fuse/dax.c
>> @@ -237,14 +237,17 @@ static int fuse_send_removemapping(struct inode *inode,
>> struct fuse_inode *fi = get_fuse_inode(inode);
>> struct fuse_mount *fm = get_fuse_mount(inode);
>> FUSE_ARGS(args);
>> + struct fuse_zero_in zero_arg;
>>
>> args.opcode = FUSE_REMOVEMAPPING;
>> args.nodeid = fi->nodeid;
>> - args.in_numargs = 2;
>> - args.in_args[0].size = sizeof(*inargp);
>> - args.in_args[0].value = inargp;
>> - args.in_args[1].size = inargp->count * sizeof(*remove_one);
>> - args.in_args[1].value = remove_one;
>> + args.in_numargs = 3;
>> + args.in_args[0].size = sizeof(zero_arg);
>> + args.in_args[0].value = &zero_arg;
>> + args.in_args[1].size = sizeof(*inargp);
>> + args.in_args[1].value = inargp;
>> + args.in_args[2].size = inargp->count * sizeof(*remove_one);
>> + args.in_args[2].value = remove_one;
>> return fuse_simple_request(fm, &args);
>> }
>>
>> diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
>> index dbc222f9b0f0e590ce3ef83077e6b4cff03cff65..6effef4073da3dad2f6140761eca98147a41d88d 100644
>> --- a/fs/fuse/dev.c
>> +++ b/fs/fuse/dev.c
>> @@ -1007,6 +1007,19 @@ static int fuse_copy_args(struct fuse_copy_state *cs, unsigned numargs,
>>
>> for (i = 0; !err && i < numargs; i++) {
>> struct fuse_arg *arg = &args[i];
>> +
>> + /* zero headers */
>> + if (arg->size == 0) {
>> + if (WARN_ON_ONCE(i != 0)) {
>> + if (cs->req)
>> + pr_err_once(
>> + "fuse: zero size header in opcode %d\n",
>> + cs->req->in.h.opcode);
>> + return -EINVAL;
>> + }
>> + continue;
>> + }
>> +
>> if (i == numargs - 1 && argpages)
>> err = fuse_copy_pages(cs, arg->size, zeroing);
>> else
>> @@ -1662,6 +1675,7 @@ static int fuse_retrieve(struct fuse_mount *fm, struct inode *inode,
>> size_t args_size = sizeof(*ra);
>> struct fuse_args_pages *ap;
>> struct fuse_args *args;
>> + struct fuse_zero_in zero_arg;
>>
>> offset = outarg->offset & ~PAGE_MASK;
>> file_size = i_size_read(inode);
>> @@ -1688,7 +1702,7 @@ static int fuse_retrieve(struct fuse_mount *fm, struct inode *inode,
>> args = &ap->args;
>> args->nodeid = outarg->nodeid;
>> args->opcode = FUSE_NOTIFY_REPLY;
>> - args->in_numargs = 2;
>> + args->in_numargs = 3;
>> args->in_pages = true;
>> args->end = fuse_retrieve_end;
>>
>> @@ -1715,9 +1729,11 @@ static int fuse_retrieve(struct fuse_mount *fm, struct inode *inode,
>> }
>> ra->inarg.offset = outarg->offset;
>> ra->inarg.size = total_len;
>> - args->in_args[0].size = sizeof(ra->inarg);
>> - args->in_args[0].value = &ra->inarg;
>> - args->in_args[1].size = total_len;
>> + args->in_args[0].size = sizeof(zero_arg);
>> + args->in_args[0].value = &zero_arg;
>> + args->in_args[1].size = sizeof(ra->inarg);
>> + args->in_args[1].value = &ra->inarg;
>> + args->in_args[2].size = total_len;
>>
>> err = fuse_simple_notify_reply(fm, args, outarg->notify_unique);
>> if (err)
>
> Do we also need to add a zero arg header for FUSE_READLINK,
> FUSE_DESTROY, and FUSE_BATCH_FORGET requests as well?
>
Thanks for looking at the patch! I should have added to the commit message
that I didn't modify these, as they don't have an in argument at all.
Thanks,
Bernd
