The userland code can pass an fd (file-descriptor) into the kernel to do some IO on (file_vnode_withvid() + vn_rdwr(), but the "other platforms" can just access the equivalent of fp->fp_glob->fg_offset; to know what offset we should start from.
I believe that all those structs are opaque. I don't see a method for accessing offset of procfd/fp/fp_glob. There are various functions like fill_fileinfo(), but looks like none of the *info functions are exported.
I was wondering if I can end up in vn_read() with FOF_OFFSET in flags, as that seems to set uio_offset to the fg_offset, and issue a zero-length read, but don't think I can get there from a fd. Has to come from fo_read() which is not exported.
Any other ideas?
Obviously, since I pass the fd from userland, I can also pass the offset - and I will probably end up doing that, it would just be a smaller "change" if I could find the offset from the kernel.
I believe that all those structs are opaque. I don't see a method for accessing offset of procfd/fp/fp_glob. There are various functions like fill_fileinfo(), but looks like none of the *info functions are exported.
I was wondering if I can end up in vn_read() with FOF_OFFSET in flags, as that seems to set uio_offset to the fg_offset, and issue a zero-length read, but don't think I can get there from a fd. Has to come from fo_read() which is not exported.
Any other ideas?
Obviously, since I pass the fd from userland, I can also pass the offset - and I will probably end up doing that, it would just be a smaller "change" if I could find the offset from the kernel.
