// SPDX-License-Identifier: GPL-2.0-only /* Network filesystem high-level write support. * * Copyright (C) 2023 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) */ #include #include #include #include #include #include #include "internal.h" /* * Determined write method. Adjust netfs_folio_traces if this is changed. */ enum netfs_how_to_modify { NETFS_FOLIO_IS_UPTODATE, /* Folio is uptodate already */ NETFS_JUST_PREFETCH, /* We have to read the folio anyway */ NETFS_WHOLE_FOLIO_MODIFY, /* We're going to overwrite the whole folio */ NETFS_MODIFY_AND_CLEAR, /* We can assume there is no data to be downloaded. */ NETFS_STREAMING_WRITE, /* Store incomplete data in non-uptodate page. */ NETFS_STREAMING_WRITE_CONT, /* Continue streaming write. */ NETFS_FLUSH_CONTENT, /* Flush incompatible content. */ }; static void netfs_cleanup_buffered_write(struct netfs_io_request *wreq); static void netfs_set_group(struct folio *folio, struct netfs_group *netfs_group) { if (netfs_group && !folio_get_private(folio)) folio_attach_private(folio, netfs_get_group(netfs_group)); } #if IS_ENABLED(CONFIG_FSCACHE) static void netfs_folio_start_fscache(bool caching, struct folio *folio) { if (caching) folio_start_fscache(folio); } #else static void netfs_folio_start_fscache(bool caching, struct folio *folio) { } #endif /* * Decide how we should modify a folio. We might be attempting to do * write-streaming, in which case we don't want to a local RMW cycle if we can * avoid it. If we're doing local caching or content crypto, we award that * priority over avoiding RMW. If the file is open readably, then we also * assume that we may want to read what we wrote. */ static enum netfs_how_to_modify netfs_how_to_modify(struct netfs_inode *ctx, struct file *file, struct folio *folio, void *netfs_group, size_t flen, size_t offset, size_t len, bool maybe_trouble) { struct netfs_folio *finfo = netfs_folio_info(folio); loff_t pos = folio_file_pos(folio); _enter(""); if (netfs_folio_group(folio) != netfs_group) return NETFS_FLUSH_CONTENT; if (folio_test_uptodate(folio)) return NETFS_FOLIO_IS_UPTODATE; if (pos >= ctx->zero_point) return NETFS_MODIFY_AND_CLEAR; if (!maybe_trouble && offset == 0 && len >= flen) return NETFS_WHOLE_FOLIO_MODIFY; if (file->f_mode & FMODE_READ) goto no_write_streaming; if (test_bit(NETFS_ICTX_NO_WRITE_STREAMING, &ctx->flags)) goto no_write_streaming; if (netfs_is_cache_enabled(ctx)) { /* We don't want to get a streaming write on a file that loses * caching service temporarily because the backing store got * culled. */ if (!test_bit(NETFS_ICTX_NO_WRITE_STREAMING, &ctx->flags)) set_bit(NETFS_ICTX_NO_WRITE_STREAMING, &ctx->flags); goto no_write_streaming; } if (!finfo) return NETFS_STREAMING_WRITE; /* We can continue a streaming write only if it continues on from the * previous. If it overlaps, we must flush lest we suffer a partial * copy and disjoint dirty regions. */ if (offset == finfo->dirty_offset + finfo->dirty_len) return NETFS_STREAMING_WRITE_CONT; return NETFS_FLUSH_CONTENT; no_write_streaming: if (finfo) { netfs_stat(&netfs_n_wh_wstream_conflict); return NETFS_FLUSH_CONTENT; } return NETFS_JUST_PREFETCH; } /* * Grab a folio for writing and lock it. Attempt to allocate as large a folio * as possible to hold as much of the remaining length as possible in one go. */ static struct folio *netfs_grab_folio_for_write(struct address_space *mapping, loff_t pos, size_t part) { pgoff_t index = pos / PAGE_SIZE; fgf_t fgp_flags = FGP_WRITEBEGIN; if (mapping_large_folio_support(mapping)) fgp_flags |= fgf_set_order(pos % PAGE_SIZE + part); return __filemap_get_folio(mapping, index, fgp_flags, mapping_gfp_mask(mapping)); } /** * netfs_perform_write - Copy data into the pagecache. * @iocb: The operation parameters * @iter: The source buffer * @netfs_group: Grouping for dirty pages (eg. ceph snaps). * * Copy data into pagecache pages attached to the inode specified by @iocb. * The caller must hold appropriate inode locks. * * Dirty pages are tagged with a netfs_folio struct if they're not up to date * to indicate the range modified. Dirty pages may also be tagged with a * netfs-specific grouping such that data from an old group gets flushed before * a new one is started. */ ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter, struct netfs_group *netfs_group) { struct file *file = iocb->ki_filp; struct inode *inode = file_inode(file); struct address_space *mapping = inode->i_mapping; struct netfs_inode *ctx = netfs_inode(inode); struct writeback_control wbc = { .sync_mode = WB_SYNC_NONE, .for_sync = true, .nr_to_write = LONG_MAX, .range_start = iocb->ki_pos, .range_end = iocb->ki_pos + iter->count, }; struct netfs_io_request *wreq = NULL; struct netfs_folio *finfo; struct folio *folio; enum netfs_how_to_modify howto; enum netfs_folio_trace trace; unsigned int bdp_flags = (iocb->ki_flags & IOCB_NOWAIT) ? BDP_ASYNC : 0; ssize_t written = 0, ret, ret2; loff_t i_size, pos = iocb->ki_pos, from, to; size_t max_chunk = PAGE_SIZE << MAX_PAGECACHE_ORDER; bool maybe_trouble = false; if (unlikely(test_bit(NETFS_ICTX_WRITETHROUGH, &ctx->flags) || iocb->ki_flags & (IOCB_DSYNC | IOCB_SYNC)) ) { wbc_attach_fdatawrite_inode(&wbc, mapping->host); ret = filemap_write_and_wait_range(mapping, pos, pos + iter->count); if (ret < 0) { wbc_detach_inode(&wbc); goto out; } wreq = netfs_begin_writethrough(iocb, iter->count); if (IS_ERR(wreq)) { wbc_detach_inode(&wbc); ret = PTR_ERR(wreq); wreq = NULL; goto out; } if (!is_sync_kiocb(iocb)) wreq->iocb = iocb; wreq->cleanup = netfs_cleanup_buffered_write; } do { size_t flen; size_t offset; /* Offset into pagecache folio */ size_t part; /* Bytes to write to folio */ size_t copied; /* Bytes copied from user */ ret = balance_dirty_pages_ratelimited_flags(mapping, bdp_flags); if (unlikely(ret < 0)) break; offset = pos & (max_chunk - 1); part = min(max_chunk - offset, iov_iter_count(iter)); /* Bring in the user pages that we will copy from _first_ lest * we hit a nasty deadlock on copying from the same page as * we're writing to, without it being marked uptodate. * * Not only is this an optimisation, but it is also required to * check that the address is actually valid, when atomic * usercopies are used below. * * We rely on the page being held onto long enough by the LRU * that we can grab it below if this causes it to be read. */ ret = -EFAULT; if (unlikely(fault_in_iov_iter_readable(iter, part) == part)) break; folio = netfs_grab_folio_for_write(mapping, pos, part); if (IS_ERR(folio)) { ret = PTR_ERR(folio); break; } flen = folio_size(folio); offset = pos & (flen - 1); part = min_t(size_t, flen - offset, part); if (signal_pending(current)) { ret = written ? -EINTR : -ERESTARTSYS; goto error_folio_unlock; } /* See if we need to prefetch the area we're going to modify. * We need to do this before we get a lock on the folio in case * there's more than one writer competing for the same cache * block. */ howto = netfs_how_to_modify(ctx, file, folio, netfs_group, flen, offset, part, maybe_trouble); _debug("howto %u", howto); switch (howto) { case NETFS_JUST_PREFETCH: ret = netfs_prefetch_for_write(file, folio, offset, part); if (ret < 0) { _debug("prefetch = %zd", ret); goto error_folio_unlock; } break; case NETFS_FOLIO_IS_UPTODATE: case NETFS_WHOLE_FOLIO_MODIFY: case NETFS_STREAMING_WRITE_CONT: break; case NETFS_MODIFY_AND_CLEAR: zero_user_segment(&folio->page, 0, offset); break; case NETFS_STREAMING_WRITE: ret = -EIO; if (WARN_ON(folio_get_private(folio))) goto error_folio_unlock; break; case NETFS_FLUSH_CONTENT: trace_netfs_folio(folio, netfs_flush_content); from = folio_pos(folio); to = from + folio_size(folio) - 1; folio_unlock(folio); folio_put(folio); ret = filemap_write_and_wait_range(mapping, from, to); if (ret < 0) goto error_folio_unlock; continue; } if (mapping_writably_mapped(mapping)) flush_dcache_folio(folio); copied = copy_folio_from_iter_atomic(folio, offset, part, iter); flush_dcache_folio(folio); /* Deal with a (partially) failed copy */ if (copied == 0) { ret = -EFAULT; goto error_folio_unlock; } trace = (enum netfs_folio_trace)howto; switch (howto) { case NETFS_FOLIO_IS_UPTODATE: case NETFS_JUST_PREFETCH: netfs_set_group(folio, netfs_group); break; case NETFS_MODIFY_AND_CLEAR: zero_user_segment(&folio->page, offset + copied, flen); netfs_set_group(folio, netfs_group); folio_mark_uptodate(folio); break; case NETFS_WHOLE_FOLIO_MODIFY: if (unlikely(copied < part)) { maybe_trouble = true; iov_iter_revert(iter, copied); copied = 0; goto retry; } netfs_set_group(folio, netfs_group); folio_mark_uptodate(folio); break; case NETFS_STREAMING_WRITE: if (offset == 0 && copied == flen) { netfs_set_group(folio, netfs_group); folio_mark_uptodate(folio); trace = netfs_streaming_filled_page; break; } finfo = kzalloc(sizeof(*finfo), GFP_KERNEL); if (!finfo) { iov_iter_revert(iter, copied); ret = -ENOMEM; goto error_folio_unlock; } finfo->netfs_group = netfs_get_group(netfs_group); finfo->dirty_offset = offset; finfo->dirty_len = copied; folio_attach_private(folio, (void *)((unsigned long)finfo | NETFS_FOLIO_INFO)); break; case NETFS_STREAMING_WRITE_CONT: finfo = netfs_folio_info(folio); finfo->dirty_len += copied; if (finfo->dirty_offset == 0 && finfo->dirty_len == flen) { if (finfo->netfs_group) folio_change_private(folio, finfo->netfs_group); else folio_detach_private(folio); folio_mark_uptodate(folio); kfree(finfo); trace = netfs_streaming_cont_filled_page; } break; default: WARN(true, "Unexpected modify type %u ix=%lx\n", howto, folio->index); ret = -EIO; goto error_folio_unlock; } trace_netfs_folio(folio, trace); /* Update the inode size if we moved the EOF marker */ i_size = i_size_read(inode); pos += copied; if (pos > i_size) { if (ctx->ops->update_i_size) { ctx->ops->update_i_size(inode, pos); } else { i_size_write(inode, pos); #if IS_ENABLED(CONFIG_FSCACHE) fscache_update_cookie(ctx->cache, NULL, &pos); #endif } } written += copied; if (likely(!wreq)) { folio_mark_dirty(folio); } else { if (folio_test_dirty(folio)) /* Sigh. mmap. */ folio_clear_dirty_for_io(folio); /* We make multiple writes to the folio... */ if (!folio_test_writeback(folio)) { folio_wait_fscache(folio); folio_start_writeback(folio); folio_start_fscache(folio); if (wreq->iter.count == 0) trace_netfs_folio(folio, netfs_folio_trace_wthru); else trace_netfs_folio(folio, netfs_folio_trace_wthru_plus); } netfs_advance_writethrough(wreq, copied, offset + copied == flen); } retry: folio_unlock(folio); folio_put(folio); folio = NULL; cond_resched(); } while (iov_iter_count(iter)); out: if (unlikely(wreq)) { ret2 = netfs_end_writethrough(wreq, iocb); wbc_detach_inode(&wbc); if (ret2 == -EIOCBQUEUED) return ret2; if (ret == 0) ret = ret2; } iocb->ki_pos += written; _leave(" = %zd [%zd]", written, ret); return written ? written : ret; error_folio_unlock: folio_unlock(folio); folio_put(folio); goto out; } EXPORT_SYMBOL(netfs_perform_write); /** * netfs_buffered_write_iter_locked - write data to a file * @iocb: IO state structure (file, offset, etc.) * @from: iov_iter with data to write * @netfs_group: Grouping for dirty pages (eg. ceph snaps). * * This function does all the work needed for actually writing data to a * file. It does all basic checks, removes SUID from the file, updates * modification times and calls proper subroutines depending on whether we * do direct IO or a standard buffered write. * * The caller must hold appropriate locks around this function and have called * generic_write_checks() already. The caller is also responsible for doing * any necessary syncing afterwards. * * This function does *not* take care of syncing data in case of O_SYNC write. * A caller has to handle it. This is mainly due to the fact that we want to * avoid syncing under i_rwsem. * * Return: * * number of bytes written, even for truncated writes * * negative error code if no data has been written at all */ ssize_t netfs_buffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *from, struct netfs_group *netfs_group) { struct file *file = iocb->ki_filp; ssize_t ret; trace_netfs_write_iter(iocb, from); ret = file_remove_privs(file); if (ret) return ret; ret = file_update_time(file); if (ret) return ret; return netfs_perform_write(iocb, from, netfs_group); } EXPORT_SYMBOL(netfs_buffered_write_iter_locked); /** * netfs_file_write_iter - write data to a file * @iocb: IO state structure * @from: iov_iter with data to write * * Perform a write to a file, writing into the pagecache if possible and doing * an unbuffered write instead if not. * * Return: * * Negative error code if no data has been written at all of * vfs_fsync_range() failed for a synchronous write * * Number of bytes written, even for truncated writes */ ssize_t netfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from) { struct file *file = iocb->ki_filp; struct inode *inode = file->f_mapping->host; struct netfs_inode *ictx = netfs_inode(inode); ssize_t ret; _enter("%llx,%zx,%llx", iocb->ki_pos, iov_iter_count(from), i_size_read(inode)); if (!iov_iter_count(from)) return 0; if ((iocb->ki_flags & IOCB_DIRECT) || test_bit(NETFS_ICTX_UNBUFFERED, &ictx->flags)) return netfs_unbuffered_write_iter(iocb, from); ret = netfs_start_io_write(inode); if (ret < 0) return ret; ret = generic_write_checks(iocb, from); if (ret > 0) ret = netfs_buffered_write_iter_locked(iocb, from, NULL); netfs_end_io_write(inode); if (ret > 0) ret = generic_write_sync(iocb, ret); return ret; } EXPORT_SYMBOL(netfs_file_write_iter); /* * Notification that a previously read-only page is about to become writable. * Note that the caller indicates a single page of a multipage folio. */ vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_group) { struct folio *folio = page_folio(vmf->page); struct file *file = vmf->vma->vm_file; struct address_space *mapping = file->f_mapping; struct inode *inode = file_inode(file); vm_fault_t ret = VM_FAULT_RETRY; int err; _enter("%lx", folio->index); sb_start_pagefault(inode->i_sb); if (folio_wait_writeback_killable(folio)) goto out; if (folio_lock_killable(folio) < 0) goto out; if (folio->mapping != mapping) { folio_unlock(folio); ret = VM_FAULT_NOPAGE; goto out; } /* Can we see a streaming write here? */ if (WARN_ON(!folio_test_uptodate(folio))) { ret = VM_FAULT_SIGBUS | VM_FAULT_LOCKED; goto out; } if (netfs_folio_group(folio) != netfs_group) { folio_unlock(folio); err = filemap_fdatawrite_range(mapping, folio_pos(folio), folio_pos(folio) + folio_size(folio)); switch (err) { case 0: ret = VM_FAULT_RETRY; goto out; case -ENOMEM: ret = VM_FAULT_OOM; goto out; default: ret = VM_FAULT_SIGBUS; goto out; } } if (folio_test_dirty(folio)) trace_netfs_folio(folio, netfs_folio_trace_mkwrite_plus); else trace_netfs_folio(folio, netfs_folio_trace_mkwrite); netfs_set_group(folio, netfs_group); file_update_time(file); ret = VM_FAULT_LOCKED; out: sb_end_pagefault(inode->i_sb); return ret; } EXPORT_SYMBOL(netfs_page_mkwrite); /* * Kill all the pages in the given range */ static void netfs_kill_pages(struct address_space *mapping, loff_t start, loff_t len) { struct folio *folio; pgoff_t index = start / PAGE_SIZE; pgoff_t last = (start + len - 1) / PAGE_SIZE, next; _enter("%llx-%llx", start, start + len - 1); do { _debug("kill %lx (to %lx)", index, last); folio = filemap_get_folio(mapping, index); if (IS_ERR(folio)) { next = index + 1; continue; } next = folio_next_index(folio); trace_netfs_folio(folio, netfs_folio_trace_kill); folio_clear_uptodate(folio); if (folio_test_fscache(folio)) folio_end_fscache(folio); folio_end_writeback(folio); folio_lock(folio); generic_error_remove_folio(mapping, folio); folio_unlock(folio); folio_put(folio); } while (index = next, index <= last); _leave(""); } /* * Redirty all the pages in a given range. */ static void netfs_redirty_pages(struct address_space *mapping, loff_t start, loff_t len) { struct folio *folio; pgoff_t index = start / PAGE_SIZE; pgoff_t last = (start + len - 1) / PAGE_SIZE, next; _enter("%llx-%llx", start, start + len - 1); do { _debug("redirty %llx @%llx", len, start); folio = filemap_get_folio(mapping, index); if (IS_ERR(folio)) { next = index + 1; continue; } next = folio_next_index(folio); trace_netfs_folio(folio, netfs_folio_trace_redirty); filemap_dirty_folio(mapping, folio); if (folio_test_fscache(folio)) folio_end_fscache(folio); folio_end_writeback(folio); folio_put(folio); } while (index = next, index <= last); balance_dirty_pages_ratelimited(mapping); _leave(""); } /* * Completion of write to server */ static void netfs_pages_written_back(struct netfs_io_request *wreq) { struct address_space *mapping = wreq->mapping; struct netfs_folio *finfo; struct netfs_group *group = NULL; struct folio *folio; pgoff_t last; int gcount = 0; XA_STATE(xas, &mapping->i_pages, wreq->start / PAGE_SIZE); _enter("%llx-%llx", wreq->start, wreq->start + wreq->len); rcu_read_lock(); last = (wreq->start + wreq->len - 1) / PAGE_SIZE; xas_for_each(&xas, folio, last) { WARN(!folio_test_writeback(folio), "bad %zx @%llx page %lx %lx\n", wreq->len, wreq->start, folio->index, last); if ((finfo = netfs_folio_info(folio))) { /* Streaming writes cannot be redirtied whilst under * writeback, so discard the streaming record. */ folio_detach_private(folio); group = finfo->netfs_group; gcount++; trace_netfs_folio(folio, netfs_folio_trace_clear_s); kfree(finfo); } else if ((group = netfs_folio_group(folio))) { /* Need to detach the group pointer if the page didn't * get redirtied. If it has been redirtied, then it * must be within the same group. */ if (folio_test_dirty(folio)) { trace_netfs_folio(folio, netfs_folio_trace_redirtied); goto end_wb; } if (folio_trylock(folio)) { if (!folio_test_dirty(folio)) { folio_detach_private(folio); gcount++; trace_netfs_folio(folio, netfs_folio_trace_clear_g); } else { trace_netfs_folio(folio, netfs_folio_trace_redirtied); } folio_unlock(folio); goto end_wb; } xas_pause(&xas); rcu_read_unlock(); folio_lock(folio); if (!folio_test_dirty(folio)) { folio_detach_private(folio); gcount++; trace_netfs_folio(folio, netfs_folio_trace_clear_g); } else { trace_netfs_folio(folio, netfs_folio_trace_redirtied); } folio_unlock(folio); rcu_read_lock(); } else { trace_netfs_folio(folio, netfs_folio_trace_clear); } end_wb: if (folio_test_fscache(folio)) folio_end_fscache(folio); xas_advance(&xas, folio_next_index(folio) - 1); folio_end_writeback(folio); } rcu_read_unlock(); netfs_put_group_many(group, gcount); _leave(""); } /* * Deal with the disposition of the folios that are under writeback to close * out the operation. */ static void netfs_cleanup_buffered_write(struct netfs_io_request *wreq) { struct address_space *mapping = wreq->mapping; _enter(""); switch (wreq->error) { case 0: netfs_pages_written_back(wreq); break; default: pr_notice("R=%08x Unexpected error %d\n", wreq->debug_id, wreq->error); fallthrough; case -EACCES: case -EPERM: case -ENOKEY: case -EKEYEXPIRED: case -EKEYREJECTED: case -EKEYREVOKED: case -ENETRESET: case -EDQUOT: case -ENOSPC: netfs_redirty_pages(mapping, wreq->start, wreq->len); break; case -EROFS: case -EIO: case -EREMOTEIO: case -EFBIG: case -ENOENT: case -ENOMEDIUM: case -ENXIO: netfs_kill_pages(mapping, wreq->start, wreq->len); break; } if (wreq->error) mapping_set_error(mapping, wreq->error); if (wreq->netfs_ops->done) wreq->netfs_ops->done(wreq); } /* * Extend the region to be written back to include subsequent contiguously * dirty pages if possible, but don't sleep while doing so. * * If this page holds new content, then we can include filler zeros in the * writeback. */ static void netfs_extend_writeback(struct address_space *mapping, struct netfs_group *group, struct xa_state *xas, long *_count, loff_t start, loff_t max_len, bool caching, size_t *_len, size_t *_top) { struct netfs_folio *finfo; struct folio_batch fbatch; struct folio *folio; unsigned int i; pgoff_t index = (start + *_len) / PAGE_SIZE; size_t len; void *priv; bool stop = true; folio_batch_init(&fbatch); do { /* Firstly, we gather up a batch of contiguous dirty pages * under the RCU read lock - but we can't clear the dirty flags * there if any of those pages are mapped. */ rcu_read_lock(); xas_for_each(xas, folio, ULONG_MAX) { stop = true; if (xas_retry(xas, folio)) continue; if (xa_is_value(folio)) break; if (folio->index != index) { xas_reset(xas); break; } if (!folio_try_get(folio)) { xas_reset(xas); continue; } /* Has the folio moved or been split? */ if (unlikely(folio != xas_reload(xas))) { folio_put(folio); xas_reset(xas); break; } if (!folio_trylock(folio)) { folio_put(folio); xas_reset(xas); break; } if (!folio_test_dirty(folio) || folio_test_writeback(folio) || folio_test_fscache(folio)) { folio_unlock(folio); folio_put(folio); xas_reset(xas); break; } stop = false; len = folio_size(folio); priv = folio_get_private(folio); if ((const struct netfs_group *)priv != group) { stop = true; finfo = netfs_folio_info(folio); if (finfo->netfs_group != group || finfo->dirty_offset > 0) { folio_unlock(folio); folio_put(folio); xas_reset(xas); break; } len = finfo->dirty_len; } *_top += folio_size(folio); index += folio_nr_pages(folio); *_count -= folio_nr_pages(folio); *_len += len; if (*_len >= max_len || *_count <= 0) stop = true; if (!folio_batch_add(&fbatch, folio)) break; if (stop) break; } xas_pause(xas); rcu_read_unlock(); /* Now, if we obtained any folios, we can shift them to being * writable and mark them for caching. */ if (!folio_batch_count(&fbatch)) break; for (i = 0; i < folio_batch_count(&fbatch); i++) { folio = fbatch.folios[i]; trace_netfs_folio(folio, netfs_folio_trace_store_plus); if (!folio_clear_dirty_for_io(folio)) BUG(); folio_start_writeback(folio); netfs_folio_start_fscache(caching, folio); folio_unlock(folio); } folio_batch_release(&fbatch); cond_resched(); } while (!stop); } /* * Synchronously write back the locked page and any subsequent non-locked dirty * pages. */ static ssize_t netfs_write_back_from_locked_folio(struct address_space *mapping, struct writeback_control *wbc, struct netfs_group *group, struct xa_state *xas, struct folio *folio, unsigned long long start, unsigned long long end) { struct netfs_io_request *wreq; struct netfs_folio *finfo; struct netfs_inode *ctx = netfs_inode(mapping->host); unsigned long long i_size = i_size_read(&ctx->inode); size_t len, max_len; bool caching = netfs_is_cache_enabled(ctx); long count = wbc->nr_to_write; int ret; _enter(",%lx,%llx-%llx,%u", folio->index, start, end, caching); wreq = netfs_alloc_request(mapping, NULL, start, folio_size(folio), NETFS_WRITEBACK); if (IS_ERR(wreq)) { folio_unlock(folio); return PTR_ERR(wreq); } if (!folio_clear_dirty_for_io(folio)) BUG(); folio_start_writeback(folio); netfs_folio_start_fscache(caching, folio); count -= folio_nr_pages(folio); /* Find all consecutive lockable dirty pages that have contiguous * written regions, stopping when we find a page that is not * immediately lockable, is not dirty or is missing, or we reach the * end of the range. */ trace_netfs_folio(folio, netfs_folio_trace_store); len = wreq->len; finfo = netfs_folio_info(folio); if (finfo) { start += finfo->dirty_offset; if (finfo->dirty_offset + finfo->dirty_len != len) { len = finfo->dirty_len; goto cant_expand; } len = finfo->dirty_len; } if (start < i_size) { /* Trim the write to the EOF; the extra data is ignored. Also * put an upper limit on the size of a single storedata op. */ max_len = 65536 * 4096; max_len = min_t(unsigned long long, max_len, end - start + 1); max_len = min_t(unsigned long long, max_len, i_size - start); if (len < max_len) netfs_extend_writeback(mapping, group, xas, &count, start, max_len, caching, &len, &wreq->upper_len); } cant_expand: len = min_t(unsigned long long, len, i_size - start); /* We now have a contiguous set of dirty pages, each with writeback * set; the first page is still locked at this point, but all the rest * have been unlocked. */ folio_unlock(folio); wreq->start = start; wreq->len = len; if (start < i_size) { _debug("write back %zx @%llx [%llx]", len, start, i_size); /* Speculatively write to the cache. We have to fix this up * later if the store fails. */ wreq->cleanup = netfs_cleanup_buffered_write; iov_iter_xarray(&wreq->iter, ITER_SOURCE, &mapping->i_pages, start, wreq->upper_len); __set_bit(NETFS_RREQ_UPLOAD_TO_SERVER, &wreq->flags); ret = netfs_begin_write(wreq, true, netfs_write_trace_writeback); if (ret == 0 || ret == -EIOCBQUEUED) wbc->nr_to_write -= len / PAGE_SIZE; } else { _debug("write discard %zx @%llx [%llx]", len, start, i_size); /* The dirty region was entirely beyond the EOF. */ fscache_clear_page_bits(mapping, start, len, caching); netfs_pages_written_back(wreq); ret = 0; } netfs_put_request(wreq, false, netfs_rreq_trace_put_return); _leave(" = 1"); return 1; } /* * Write a region of pages back to the server */ static ssize_t netfs_writepages_begin(struct address_space *mapping, struct writeback_control *wbc, struct netfs_group *group, struct xa_state *xas, unsigned long long *_start, unsigned long long end) { const struct netfs_folio *finfo; struct folio *folio; unsigned long long start = *_start; ssize_t ret; void *priv; int skips = 0; _enter("%llx,%llx,", start, end); search_again: /* Find the first dirty page in the group. */ rcu_read_lock(); for (;;) { folio = xas_find_marked(xas, end / PAGE_SIZE, PAGECACHE_TAG_DIRTY); if (xas_retry(xas, folio) || xa_is_value(folio)) continue; if (!folio) break; if (!folio_try_get(folio)) { xas_reset(xas); continue; } if (unlikely(folio != xas_reload(xas))) { folio_put(folio); xas_reset(xas); continue; } /* Skip any dirty folio that's not in the group of interest. */ priv = folio_get_private(folio); if ((const struct netfs_group *)priv != group) { finfo = netfs_folio_info(folio); if (finfo->netfs_group != group) { folio_put(folio); continue; } } xas_pause(xas); break; } rcu_read_unlock(); if (!folio) return 0; start = folio_pos(folio); /* May regress with THPs */ _debug("wback %lx", folio->index); /* At this point we hold neither the i_pages lock nor the page lock: * the page may be truncated or invalidated (changing page->mapping to * NULL), or even swizzled back from swapper_space to tmpfs file * mapping */ lock_again: if (wbc->sync_mode != WB_SYNC_NONE) { ret = folio_lock_killable(folio); if (ret < 0) return ret; } else { if (!folio_trylock(folio)) goto search_again; } if (folio->mapping != mapping || !folio_test_dirty(folio)) { start += folio_size(folio); folio_unlock(folio); goto search_again; } if (folio_test_writeback(folio) || folio_test_fscache(folio)) { folio_unlock(folio); if (wbc->sync_mode != WB_SYNC_NONE) { folio_wait_writeback(folio); #ifdef CONFIG_FSCACHE folio_wait_fscache(folio); #endif goto lock_again; } start += folio_size(folio); if (wbc->sync_mode == WB_SYNC_NONE) { if (skips >= 5 || need_resched()) { ret = 0; goto out; } skips++; } goto search_again; } ret = netfs_write_back_from_locked_folio(mapping, wbc, group, xas, folio, start, end); out: if (ret > 0) *_start = start + ret; _leave(" = %zd [%llx]", ret, *_start); return ret; } /* * Write a region of pages back to the server */ static int netfs_writepages_region(struct address_space *mapping, struct writeback_control *wbc, struct netfs_group *group, unsigned long long *_start, unsigned long long end) { ssize_t ret; XA_STATE(xas, &mapping->i_pages, *_start / PAGE_SIZE); do { ret = netfs_writepages_begin(mapping, wbc, group, &xas, _start, end); if (ret > 0 && wbc->nr_to_write > 0) cond_resched(); } while (ret > 0 && wbc->nr_to_write > 0); return ret > 0 ? 0 : ret; } /* * write some of the pending data back to the server */ int netfs_writepages(struct address_space *mapping, struct writeback_control *wbc) { struct netfs_group *group = NULL; loff_t start, end; int ret; _enter(""); /* We have to be careful as we can end up racing with setattr() * truncating the pagecache since the caller doesn't take a lock here * to prevent it. */ if (wbc->range_cyclic && mapping->writeback_index) { start = mapping->writeback_index * PAGE_SIZE; ret = netfs_writepages_region(mapping, wbc, group, &start, LLONG_MAX); if (ret < 0) goto out; if (wbc->nr_to_write <= 0) { mapping->writeback_index = start / PAGE_SIZE; goto out; } start = 0; end = mapping->writeback_index * PAGE_SIZE; mapping->writeback_index = 0; ret = netfs_writepages_region(mapping, wbc, group, &start, end); if (ret == 0) mapping->writeback_index = start / PAGE_SIZE; } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) { start = 0; ret = netfs_writepages_region(mapping, wbc, group, &start, LLONG_MAX); if (wbc->nr_to_write > 0 && ret == 0) mapping->writeback_index = start / PAGE_SIZE; } else { start = wbc->range_start; ret = netfs_writepages_region(mapping, wbc, group, &start, wbc->range_end); } out: _leave(" = %d", ret); return ret; } EXPORT_SYMBOL(netfs_writepages); /* * Deal with the disposition of a laundered folio. */ static void netfs_cleanup_launder_folio(struct netfs_io_request *wreq) { if (wreq->error) { pr_notice("R=%08x Laundering error %d\n", wreq->debug_id, wreq->error); mapping_set_error(wreq->mapping, wreq->error); } } /** * netfs_launder_folio - Clean up a dirty folio that's being invalidated * @folio: The folio to clean * * This is called to write back a folio that's being invalidated when an inode * is getting torn down. Ideally, writepages would be used instead. */ int netfs_launder_folio(struct folio *folio) { struct netfs_io_request *wreq; struct address_space *mapping = folio->mapping; struct netfs_folio *finfo = netfs_folio_info(folio); struct netfs_group *group = netfs_folio_group(folio); struct bio_vec bvec; unsigned long long i_size = i_size_read(mapping->host); unsigned long long start = folio_pos(folio); size_t offset = 0, len; int ret = 0; if (finfo) { offset = finfo->dirty_offset; start += offset; len = finfo->dirty_len; } else { len = folio_size(folio); } len = min_t(unsigned long long, len, i_size - start); wreq = netfs_alloc_request(mapping, NULL, start, len, NETFS_LAUNDER_WRITE); if (IS_ERR(wreq)) { ret = PTR_ERR(wreq); goto out; } if (!folio_clear_dirty_for_io(folio)) goto out_put; trace_netfs_folio(folio, netfs_folio_trace_launder); _debug("launder %llx-%llx", start, start + len - 1); /* Speculatively write to the cache. We have to fix this up later if * the store fails. */ wreq->cleanup = netfs_cleanup_launder_folio; bvec_set_folio(&bvec, folio, len, offset); iov_iter_bvec(&wreq->iter, ITER_SOURCE, &bvec, 1, len); __set_bit(NETFS_RREQ_UPLOAD_TO_SERVER, &wreq->flags); ret = netfs_begin_write(wreq, true, netfs_write_trace_launder); out_put: folio_detach_private(folio); netfs_put_group(group); kfree(finfo); netfs_put_request(wreq, false, netfs_rreq_trace_put_return); out: folio_wait_fscache(folio); _leave(" = %d", ret); return ret; } EXPORT_SYMBOL(netfs_launder_folio);