static int ll_write_begin(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, unsigned flags, struct page **pagep, void **fsdata) { struct ll_cl_context *lcc; const struct lu_env *env = NULL; struct cl_io *io; struct cl_page *page = NULL; struct cl_object *clob = ll_i2info(mapping->host)->lli_clob; pgoff_t index = pos >> PAGE_SHIFT; struct page *vmpage = NULL; unsigned from = pos & (PAGE_SIZE - 1); unsigned to = from + len; int result = 0; ENTRY; CDEBUG(D_VFSTRACE, "Writing %lu of %d to %d bytes\n", index, from, len); lcc = ll_cl_find(file); if (lcc == NULL) { io = NULL; GOTO(out, result = -EIO); } env = lcc->lcc_env; io = lcc->lcc_io; /* To avoid deadlock, try to lock page first. */ vmpage = grab_cache_page_nowait(mapping, index); if (unlikely(vmpage == NULL || PageDirty(vmpage) || PageWriteback(vmpage))) { struct vvp_io *vio = vvp_env_io(env); struct cl_page_list *plist = &vio->u.write.vui_queue; /* if the page is already in dirty cache, we have to commit * the pages right now; otherwise, it may cause deadlock * because it holds page lock of a dirty page and request for * more grants. It's okay for the dirty page to be the first * one in commit page list, though. */ if (vmpage != NULL && plist->pl_nr > 0) { unlock_page(vmpage); put_page(vmpage); vmpage = NULL; } /* commit pages and then wait for page lock */ result = vvp_io_write_commit(env, io); if (result < 0) GOTO(out, result); if (vmpage == NULL) { vmpage = grab_cache_page_write_begin(mapping, index, flags); if (vmpage == NULL) GOTO(out, result = -ENOMEM); } } page = cl_page_find(env, clob, vmpage->index, vmpage, CPT_CACHEABLE); if (IS_ERR(page)) GOTO(out, result = PTR_ERR(page)); lcc->lcc_page = page; lu_ref_add(&page->cp_reference, "cl_io", io); cl_page_assume(env, io, page); if (!PageUptodate(vmpage)) { /* * We're completely overwriting an existing page, * so _don't_ set it up to date until commit_write */ if (from == 0 && to == PAGE_SIZE) { CL_PAGE_HEADER(D_PAGE, env, page, "full page write\n"); POISON_PAGE(vmpage, 0x11); } else { /* TODO: can be optimized at OSC layer to check if it * is a lockless IO. In that case, it's not necessary * to read the data. */ result = ll_prepare_partial_page(env, io, page); if (result == 0) SetPageUptodate(vmpage); } } if (result < 0) cl_page_unassume(env, io, page); EXIT; out: if (result < 0) { if (vmpage != NULL) { unlock_page(vmpage); put_page(vmpage); } if (!IS_ERR_OR_NULL(page)) { lu_ref_del(&page->cp_reference, "cl_io", io); cl_page_put(env, page); } if (io) io->ci_result = result; } else { *pagep = vmpage; *fsdata = lcc; } RETURN(result); }
static int vvp_io_fault_start(const struct lu_env *env, const struct cl_io_slice *ios) { struct vvp_io *vio = cl2vvp_io(env, ios); struct cl_io *io = ios->cis_io; struct cl_object *obj = io->ci_obj; struct inode *inode = ccc_object_inode(obj); struct cl_fault_io *fio = &io->u.ci_fault; struct vvp_fault_io *cfio = &vio->u.fault; loff_t offset; int result = 0; struct page *vmpage = NULL; struct cl_page *page; loff_t size; pgoff_t last; /* last page in a file data region */ if (fio->ft_executable && LTIME_S(inode->i_mtime) != vio->u.fault.ft_mtime) CWARN("binary "DFID " changed while waiting for the page fault lock\n", PFID(lu_object_fid(&obj->co_lu))); /* offset of the last byte on the page */ offset = cl_offset(obj, fio->ft_index + 1) - 1; LASSERT(cl_index(obj, offset) == fio->ft_index); result = ccc_prep_size(env, obj, io, 0, offset + 1, NULL); if (result != 0) return result; /* must return locked page */ if (fio->ft_mkwrite) { LASSERT(cfio->ft_vmpage != NULL); lock_page(cfio->ft_vmpage); } else { result = vvp_io_kernel_fault(cfio); if (result != 0) return result; } vmpage = cfio->ft_vmpage; LASSERT(PageLocked(vmpage)); if (OBD_FAIL_CHECK(OBD_FAIL_LLITE_FAULT_TRUNC_RACE)) ll_invalidate_page(vmpage); size = i_size_read(inode); /* Though we have already held a cl_lock upon this page, but * it still can be truncated locally. */ if (unlikely((vmpage->mapping != inode->i_mapping) || (page_offset(vmpage) > size))) { CDEBUG(D_PAGE, "llite: fault and truncate race happened!\n"); /* return +1 to stop cl_io_loop() and ll_fault() will catch * and retry. */ GOTO(out, result = +1); } if (fio->ft_mkwrite ) { pgoff_t last_index; /* * Capture the size while holding the lli_trunc_sem from above * we want to make sure that we complete the mkwrite action * while holding this lock. We need to make sure that we are * not past the end of the file. */ last_index = cl_index(obj, size - 1); if (last_index < fio->ft_index) { CDEBUG(D_PAGE, "llite: mkwrite and truncate race happened: " "%p: 0x%lx 0x%lx\n", vmpage->mapping,fio->ft_index,last_index); /* * We need to return if we are * passed the end of the file. This will propagate * up the call stack to ll_page_mkwrite where * we will return VM_FAULT_NOPAGE. Any non-negative * value returned here will be silently * converted to 0. If the vmpage->mapping is null * the error code would be converted back to ENODATA * in ll_page_mkwrite0. Thus we return -ENODATA * to handle both cases */ GOTO(out, result = -ENODATA); } } page = cl_page_find(env, obj, fio->ft_index, vmpage, CPT_CACHEABLE); if (IS_ERR(page)) GOTO(out, result = PTR_ERR(page)); /* if page is going to be written, we should add this page into cache * earlier. */ if (fio->ft_mkwrite) { wait_on_page_writeback(vmpage); if (set_page_dirty(vmpage)) { struct ccc_page *cp; /* vvp_page_assume() calls wait_on_page_writeback(). */ cl_page_assume(env, io, page); cp = cl2ccc_page(cl_page_at(page, &vvp_device_type)); vvp_write_pending(cl2ccc(obj), cp); /* Do not set Dirty bit here so that in case IO is * started before the page is really made dirty, we * still have chance to detect it. */ result = cl_page_cache_add(env, io, page, CRT_WRITE); LASSERT(cl_page_is_owned(page, io)); vmpage = NULL; if (result < 0) { cl_page_unmap(env, io, page); cl_page_discard(env, io, page); cl_page_disown(env, io, page); cl_page_put(env, page); /* we're in big trouble, what can we do now? */ if (result == -EDQUOT) result = -ENOSPC; GOTO(out, result); } else cl_page_disown(env, io, page); } } last = cl_index(obj, size - 1); /* * The ft_index is only used in the case of * a mkwrite action. We need to check * our assertions are correct, since * we should have caught this above */ LASSERT(!fio->ft_mkwrite || fio->ft_index <= last); if (fio->ft_index == last) /* * Last page is mapped partially. */ fio->ft_nob = size - cl_offset(obj, fio->ft_index); else fio->ft_nob = cl_page_size(obj); lu_ref_add(&page->cp_reference, "fault", io); fio->ft_page = page; EXIT; out: /* return unlocked vmpage to avoid deadlocking */ if (vmpage != NULL) unlock_page(vmpage); cfio->fault.ft_flags &= ~VM_FAULT_LOCKED; return result; }