diff --git a/Documentation/devices.txt b/Documentation/devices.txt index 23721d3be3e6..80b72419ffd8 100644 --- a/Documentation/devices.txt +++ b/Documentation/devices.txt @@ -414,6 +414,7 @@ Your cooperation is appreciated. 200 = /dev/net/tun TAP/TUN network device 201 = /dev/button/gulpb Transmeta GULP-B buttons 202 = /dev/emd/ctl Enhanced Metadisk RAID (EMD) control + 203 = /dev/cuse Cuse (character device in user-space) 204 = /dev/video/em8300 EM8300 DVD decoder control 205 = /dev/video/em8300_mv EM8300 DVD decoder video 206 = /dev/video/em8300_ma EM8300 DVD decoder audio diff --git a/fs/fuse/cuse.c b/fs/fuse/cuse.c index adbfd66b380f..24da581cb52b 100644 --- a/fs/fuse/cuse.c +++ b/fs/fuse/cuse.c @@ -589,11 +589,14 @@ static struct attribute *cuse_class_dev_attrs[] = { ATTRIBUTE_GROUPS(cuse_class_dev); static struct miscdevice cuse_miscdev = { - .minor = MISC_DYNAMIC_MINOR, + .minor = CUSE_MINOR, .name = "cuse", .fops = &cuse_channel_fops, }; +MODULE_ALIAS_MISCDEV(CUSE_MINOR); +MODULE_ALIAS("devname:cuse"); + static int __init cuse_init(void) { int i, rc; diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 4598345ab87d..7e70506297bc 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -334,7 +334,8 @@ static bool fuse_page_is_writeback(struct inode *inode, pgoff_t index) BUG_ON(req->inode != inode); curr_index = req->misc.write.in.offset >> PAGE_CACHE_SHIFT; - if (curr_index == index) { + if (curr_index <= index && + index < curr_index + req->num_pages) { found = true; break; } @@ -1409,8 +1410,13 @@ static ssize_t fuse_direct_write(struct file *file, const char __user *buf, static void fuse_writepage_free(struct fuse_conn *fc, struct fuse_req *req) { - __free_page(req->pages[0]); - fuse_file_put(req->ff, false); + int i; + + for (i = 0; i < req->num_pages; i++) + __free_page(req->pages[i]); + + if (req->ff) + fuse_file_put(req->ff, false); } static void fuse_writepage_finish(struct fuse_conn *fc, struct fuse_req *req) @@ -1418,30 +1424,34 @@ static void fuse_writepage_finish(struct fuse_conn *fc, struct fuse_req *req) struct inode *inode = req->inode; struct fuse_inode *fi = get_fuse_inode(inode); struct backing_dev_info *bdi = inode->i_mapping->backing_dev_info; + int i; list_del(&req->writepages_entry); - dec_bdi_stat(bdi, BDI_WRITEBACK); - dec_zone_page_state(req->pages[0], NR_WRITEBACK_TEMP); - bdi_writeout_inc(bdi); + for (i = 0; i < req->num_pages; i++) { + dec_bdi_stat(bdi, BDI_WRITEBACK); + dec_zone_page_state(req->pages[i], NR_WRITEBACK_TEMP); + bdi_writeout_inc(bdi); + } wake_up(&fi->page_waitq); } /* Called under fc->lock, may release and reacquire it */ -static void fuse_send_writepage(struct fuse_conn *fc, struct fuse_req *req) +static void fuse_send_writepage(struct fuse_conn *fc, struct fuse_req *req, + loff_t size) __releases(fc->lock) __acquires(fc->lock) { struct fuse_inode *fi = get_fuse_inode(req->inode); - loff_t size = i_size_read(req->inode); struct fuse_write_in *inarg = &req->misc.write.in; + __u64 data_size = req->num_pages * PAGE_CACHE_SIZE; if (!fc->connected) goto out_free; - if (inarg->offset + PAGE_CACHE_SIZE <= size) { - inarg->size = PAGE_CACHE_SIZE; + if (inarg->offset + data_size <= size) { + inarg->size = data_size; } else if (inarg->offset < size) { - inarg->size = size & (PAGE_CACHE_SIZE - 1); + inarg->size = size - inarg->offset; } else { /* Got truncated off completely */ goto out_free; @@ -1472,12 +1482,13 @@ __acquires(fc->lock) { struct fuse_conn *fc = get_fuse_conn(inode); struct fuse_inode *fi = get_fuse_inode(inode); + size_t crop = i_size_read(inode); struct fuse_req *req; while (fi->writectr >= 0 && !list_empty(&fi->queued_writes)) { req = list_entry(fi->queued_writes.next, struct fuse_req, list); list_del_init(&req->list); - fuse_send_writepage(fc, req); + fuse_send_writepage(fc, req, crop); } } @@ -1488,12 +1499,62 @@ static void fuse_writepage_end(struct fuse_conn *fc, struct fuse_req *req) mapping_set_error(inode->i_mapping, req->out.h.error); spin_lock(&fc->lock); + while (req->misc.write.next) { + struct fuse_conn *fc = get_fuse_conn(inode); + struct fuse_write_in *inarg = &req->misc.write.in; + struct fuse_req *next = req->misc.write.next; + req->misc.write.next = next->misc.write.next; + next->misc.write.next = NULL; + next->ff = fuse_file_get(req->ff); + list_add(&next->writepages_entry, &fi->writepages); + + /* + * Skip fuse_flush_writepages() to make it easy to crop requests + * based on primary request size. + * + * 1st case (trivial): there are no concurrent activities using + * fuse_set/release_nowrite. Then we're on safe side because + * fuse_flush_writepages() would call fuse_send_writepage() + * anyway. + * + * 2nd case: someone called fuse_set_nowrite and it is waiting + * now for completion of all in-flight requests. This happens + * rarely and no more than once per page, so this should be + * okay. + * + * 3rd case: someone (e.g. fuse_do_setattr()) is in the middle + * of fuse_set_nowrite..fuse_release_nowrite section. The fact + * that fuse_set_nowrite returned implies that all in-flight + * requests were completed along with all of their secondary + * requests. Further primary requests are blocked by negative + * writectr. Hence there cannot be any in-flight requests and + * no invocations of fuse_writepage_end() while we're in + * fuse_set_nowrite..fuse_release_nowrite section. + */ + fuse_send_writepage(fc, next, inarg->offset + inarg->size); + } fi->writectr--; fuse_writepage_finish(fc, req); spin_unlock(&fc->lock); fuse_writepage_free(fc, req); } +static struct fuse_file *fuse_write_file_get(struct fuse_conn *fc, + struct fuse_inode *fi) +{ + struct fuse_file *ff = NULL; + + spin_lock(&fc->lock); + if (!WARN_ON(list_empty(&fi->write_files))) { + ff = list_entry(fi->write_files.next, struct fuse_file, + write_entry); + fuse_file_get(ff); + } + spin_unlock(&fc->lock); + + return ff; +} + static int fuse_writepage_locked(struct page *page) { struct address_space *mapping = page->mapping; @@ -1501,8 +1562,8 @@ static int fuse_writepage_locked(struct page *page) struct fuse_conn *fc = get_fuse_conn(inode); struct fuse_inode *fi = get_fuse_inode(inode); struct fuse_req *req; - struct fuse_file *ff; struct page *tmp_page; + int error = -ENOMEM; set_page_writeback(page); @@ -1515,16 +1576,16 @@ static int fuse_writepage_locked(struct page *page) if (!tmp_page) goto err_free; - spin_lock(&fc->lock); - BUG_ON(list_empty(&fi->write_files)); - ff = list_entry(fi->write_files.next, struct fuse_file, write_entry); - req->ff = fuse_file_get(ff); - spin_unlock(&fc->lock); + error = -EIO; + req->ff = fuse_write_file_get(fc, fi); + if (!req->ff) + goto err_free; - fuse_write_fill(req, ff, page_offset(page), 0); + fuse_write_fill(req, req->ff, page_offset(page), 0); copy_highpage(tmp_page, page); req->misc.write.in.write_flags |= FUSE_WRITE_CACHE; + req->misc.write.next = NULL; req->in.argpages = 1; req->num_pages = 1; req->pages[0] = tmp_page; @@ -1550,19 +1611,263 @@ static int fuse_writepage_locked(struct page *page) fuse_request_free(req); err: end_page_writeback(page); - return -ENOMEM; + return error; } static int fuse_writepage(struct page *page, struct writeback_control *wbc) { int err; + if (fuse_page_is_writeback(page->mapping->host, page->index)) { + /* + * ->writepages() should be called for sync() and friends. We + * should only get here on direct reclaim and then we are + * allowed to skip a page which is already in flight + */ + WARN_ON(wbc->sync_mode == WB_SYNC_ALL); + + redirty_page_for_writepage(wbc, page); + return 0; + } + err = fuse_writepage_locked(page); unlock_page(page); return err; } +struct fuse_fill_wb_data { + struct fuse_req *req; + struct fuse_file *ff; + struct inode *inode; + struct page **orig_pages; +}; + +static void fuse_writepages_send(struct fuse_fill_wb_data *data) +{ + struct fuse_req *req = data->req; + struct inode *inode = data->inode; + struct fuse_conn *fc = get_fuse_conn(inode); + struct fuse_inode *fi = get_fuse_inode(inode); + int num_pages = req->num_pages; + int i; + + req->ff = fuse_file_get(data->ff); + spin_lock(&fc->lock); + list_add_tail(&req->list, &fi->queued_writes); + fuse_flush_writepages(inode); + spin_unlock(&fc->lock); + + for (i = 0; i < num_pages; i++) + end_page_writeback(data->orig_pages[i]); +} + +static bool fuse_writepage_in_flight(struct fuse_req *new_req, + struct page *page) +{ + struct fuse_conn *fc = get_fuse_conn(new_req->inode); + struct fuse_inode *fi = get_fuse_inode(new_req->inode); + struct fuse_req *tmp; + struct fuse_req *old_req; + bool found = false; + pgoff_t curr_index; + + BUG_ON(new_req->num_pages != 0); + + spin_lock(&fc->lock); + list_del(&new_req->writepages_entry); + list_for_each_entry(old_req, &fi->writepages, writepages_entry) { + BUG_ON(old_req->inode != new_req->inode); + curr_index = old_req->misc.write.in.offset >> PAGE_CACHE_SHIFT; + if (curr_index <= page->index && + page->index < curr_index + old_req->num_pages) { + found = true; + break; + } + } + if (!found) { + list_add(&new_req->writepages_entry, &fi->writepages); + goto out_unlock; + } + + new_req->num_pages = 1; + for (tmp = old_req; tmp != NULL; tmp = tmp->misc.write.next) { + BUG_ON(tmp->inode != new_req->inode); + curr_index = tmp->misc.write.in.offset >> PAGE_CACHE_SHIFT; + if (tmp->num_pages == 1 && + curr_index == page->index) { + old_req = tmp; + } + } + + if (old_req->num_pages == 1 && (old_req->state == FUSE_REQ_INIT || + old_req->state == FUSE_REQ_PENDING)) { + struct backing_dev_info *bdi = page->mapping->backing_dev_info; + + copy_highpage(old_req->pages[0], page); + spin_unlock(&fc->lock); + + dec_bdi_stat(bdi, BDI_WRITEBACK); + dec_zone_page_state(page, NR_WRITEBACK_TEMP); + bdi_writeout_inc(bdi); + fuse_writepage_free(fc, new_req); + fuse_request_free(new_req); + goto out; + } else { + new_req->misc.write.next = old_req->misc.write.next; + old_req->misc.write.next = new_req; + } +out_unlock: + spin_unlock(&fc->lock); +out: + return found; +} + +static int fuse_writepages_fill(struct page *page, + struct writeback_control *wbc, void *_data) +{ + struct fuse_fill_wb_data *data = _data; + struct fuse_req *req = data->req; + struct inode *inode = data->inode; + struct fuse_conn *fc = get_fuse_conn(inode); + struct page *tmp_page; + bool is_writeback; + int err; + + if (!data->ff) { + err = -EIO; + data->ff = fuse_write_file_get(fc, get_fuse_inode(inode)); + if (!data->ff) + goto out_unlock; + } + + /* + * Being under writeback is unlikely but possible. For example direct + * read to an mmaped fuse file will set the page dirty twice; once when + * the pages are faulted with get_user_pages(), and then after the read + * completed. + */ + is_writeback = fuse_page_is_writeback(inode, page->index); + + if (req && req->num_pages && + (is_writeback || req->num_pages == FUSE_MAX_PAGES_PER_REQ || + (req->num_pages + 1) * PAGE_CACHE_SIZE > fc->max_write || + data->orig_pages[req->num_pages - 1]->index + 1 != page->index)) { + fuse_writepages_send(data); + data->req = NULL; + } + err = -ENOMEM; + tmp_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM); + if (!tmp_page) + goto out_unlock; + + /* + * The page must not be redirtied until the writeout is completed + * (i.e. userspace has sent a reply to the write request). Otherwise + * there could be more than one temporary page instance for each real + * page. + * + * This is ensured by holding the page lock in page_mkwrite() while + * checking fuse_page_is_writeback(). We already hold the page lock + * since clear_page_dirty_for_io() and keep it held until we add the + * request to the fi->writepages list and increment req->num_pages. + * After this fuse_page_is_writeback() will indicate that the page is + * under writeback, so we can release the page lock. + */ + if (data->req == NULL) { + struct fuse_inode *fi = get_fuse_inode(inode); + + err = -ENOMEM; + req = fuse_request_alloc_nofs(FUSE_MAX_PAGES_PER_REQ); + if (!req) { + __free_page(tmp_page); + goto out_unlock; + } + + fuse_write_fill(req, data->ff, page_offset(page), 0); + req->misc.write.in.write_flags |= FUSE_WRITE_CACHE; + req->misc.write.next = NULL; + req->in.argpages = 1; + req->background = 1; + req->num_pages = 0; + req->end = fuse_writepage_end; + req->inode = inode; + + spin_lock(&fc->lock); + list_add(&req->writepages_entry, &fi->writepages); + spin_unlock(&fc->lock); + + data->req = req; + } + set_page_writeback(page); + + copy_highpage(tmp_page, page); + req->pages[req->num_pages] = tmp_page; + req->page_descs[req->num_pages].offset = 0; + req->page_descs[req->num_pages].length = PAGE_SIZE; + + inc_bdi_stat(page->mapping->backing_dev_info, BDI_WRITEBACK); + inc_zone_page_state(tmp_page, NR_WRITEBACK_TEMP); + + err = 0; + if (is_writeback && fuse_writepage_in_flight(req, page)) { + end_page_writeback(page); + data->req = NULL; + goto out_unlock; + } + data->orig_pages[req->num_pages] = page; + + /* + * Protected by fc->lock against concurrent access by + * fuse_page_is_writeback(). + */ + spin_lock(&fc->lock); + req->num_pages++; + spin_unlock(&fc->lock); + +out_unlock: + unlock_page(page); + + return err; +} + +static int fuse_writepages(struct address_space *mapping, + struct writeback_control *wbc) +{ + struct inode *inode = mapping->host; + struct fuse_fill_wb_data data; + int err; + + err = -EIO; + if (is_bad_inode(inode)) + goto out; + + data.inode = inode; + data.req = NULL; + data.ff = NULL; + + err = -ENOMEM; + data.orig_pages = kzalloc(sizeof(struct page *) * + FUSE_MAX_PAGES_PER_REQ, + GFP_NOFS); + if (!data.orig_pages) + goto out; + + err = write_cache_pages(mapping, wbc, fuse_writepages_fill, &data); + if (data.req) { + /* Ignore errors if we can write at least one page */ + BUG_ON(!data.req->num_pages); + fuse_writepages_send(&data); + err = 0; + } + if (data.ff) + fuse_file_put(data.ff, false); + + kfree(data.orig_pages); +out: + return err; +} + static int fuse_launder_page(struct page *page) { int err = 0; @@ -1602,14 +1907,17 @@ static void fuse_vma_close(struct vm_area_struct *vma) static int fuse_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) { struct page *page = vmf->page; - /* - * Don't use page->mapping as it may become NULL from a - * concurrent truncate. - */ - struct inode *inode = vma->vm_file->f_mapping->host; + struct inode *inode = file_inode(vma->vm_file); + + file_update_time(vma->vm_file); + lock_page(page); + if (page->mapping != inode->i_mapping) { + unlock_page(page); + return VM_FAULT_NOPAGE; + } fuse_wait_on_page_writeback(inode, page->index); - return 0; + return VM_FAULT_LOCKED; } static const struct vm_operations_struct fuse_file_vm_ops = { @@ -2581,6 +2889,7 @@ static const struct file_operations fuse_direct_io_file_operations = { static const struct address_space_operations fuse_file_aops = { .readpage = fuse_readpage, .writepage = fuse_writepage, + .writepages = fuse_writepages, .launder_page = fuse_launder_page, .readpages = fuse_readpages, .set_page_dirty = __set_page_dirty_nobuffers, diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index 5b9e6f3b6aef..643274852c8b 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -321,6 +321,7 @@ struct fuse_req { struct { struct fuse_write_in in; struct fuse_write_out out; + struct fuse_req *next; } write; struct fuse_notify_retrieve_in retrieve_in; struct fuse_lk_in lk_in; diff --git a/include/linux/miscdevice.h b/include/linux/miscdevice.h index cb358355ef43..f7eaf2d60083 100644 --- a/include/linux/miscdevice.h +++ b/include/linux/miscdevice.h @@ -31,6 +31,7 @@ #define I2O_MINOR 166 #define MICROCODE_MINOR 184 #define TUN_MINOR 200 +#define CUSE_MINOR 203 #define MWAVE_MINOR 219 /* ACP/Mwave Modem */ #define MPT_MINOR 220 #define MPT2SAS_MINOR 221