[NFS-Ganesha-Support] Re: Proxy FSAL - NFS4 -> 3

On Sat, Jul 3, 2021 at 10:08 PM Nick Couchman <nick.e.couchman(a)gmail.com wrote: > On Tue, Jun 29, 2021 at 11:52 PM Solomon Boulos <boulos(a)google.com> wrote: >> Alright, looking through some git blame -w, I think this broke and then >> was restored in 2912fad98e. Jim had a diff in 2014 (823625c5da) to make the >> code compile, but crucially the buffer code no longer had a “max len” just >> a length. >>> I think this broke the “clever” reuse of the input buffdesc as the >> argument to GetFH (which has been there since 2012 from 878f45493e). >>> The input when mapped is a 16-byte thingy (sizeof nfs23_map_handle_t), >> and GetFH needs to expand the 16-byte mapped handle into an FH4. I assume >> the code when written had a FH4_SIZE as it’s max length, rather than the >> fh_desc buffer appearing to be trimmed to 16-bytes (that is, I think there >> was a length separate from max length at the time or something). >>> Digging into this a little more, I think the following commit actually > originally broke things: > 3016c4cee45635afa9c25b21c2f5b014d80d1b6d > In that commit, the "netbuf" data type used as an argument > for HandleMap_GetFH is replaced with the "gsh_buffdesc" data type. As far > as I can tell, "gsh_buffdesc" never had a "maxlen" member, so the following > code in that function would not have compiled after that: > == > ... > if(rc == HASHTABLE_SUCCESS) > { > handle_pool_entry_t *h = (handle_pool_entry_t *)buffval.pdata; > if(h->fh_len < p_out_fsal_handle->maxlen) > { > p_out_fsal_handle->len = h->fh_len; > memcpy(p_out_fsal_handle->buf, h->fh_data, h->fh_len); > memcpy(p_out_fsal_handle->addr, h->fh_data, h->fh_len); > rc = HANDLEMAP_SUCCESS; > } > ... > == > After that change, there are various iterations of renaming the > "p_out_fsal_handle" parameter to other things, up until the commit that you > mentioned that fixed the compile issues > (823625c5da2373606dd4f75dce46a92be143507c), which resulted in the code > having "p_out_fsal_handle" renamed to the value actually being passed in, > and the "maxlen" member replaced with "len". And, just another note on this - in the commit prior to 3016c4cee4, I believe the netbuf that gets passed around is allocated in this block of code: == fsal_status_t pxy_create_handle(struct fsal_export *exp_hdl, struct fsal_handle_desc *hdl_desc, struct fsal_obj_handle **handle) { fsal_status_t st; nfs_fh4 fh4; fsal_attrib_list_t attr; struct pxy_obj_handle *ph; #ifdef _HANDLE_MAPPING char fh_data[NFS4_FHSIZE+2]; #endif if(!exp_hdl || !hdl_desc || !handle || (hdl_desc->len NFS4_FHSIZE)) ReturnCode(ERR_FSAL_INVAL, 0); fh4.nfs_fh4_val = hdl_desc->start; fh4.nfs_fh4_len = hdl_desc->len; #ifdef _HANDLE_MAPPING if(hdl_desc->len == sizeof(nfs23_map_handle_t)) { nfs23_map_handle_t *h23 = (nfs23_map_handle_t*)hdl_desc->start; if(h23->type == PXY_HANDLE_MAPPED) { struct netbuf fh = { .maxlen = sizeof(fh_data), .buf = fh_data }; struct pxy_handle_blob *blob; == From this I gather that the size of maxlen for that netbuf is the size of the data going into the buffer; however, that member is allocated as NFS4_FHSIZE + 2. So, maybe a constant, something like: #define PROXYV4_HANDLE_MAXLEN NFS4_FHSIZE+2

Or maybe there's a better way?