--- /dev/null
- generic_error_remove_page(mapping, &folio->page);
+ // 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 <linux/export.h>
+ #include <linux/fs.h>
+ #include <linux/mm.h>
+ #include <linux/pagemap.h>
+ #include <linux/slab.h>
+ #include <linux/pagevec.h>
+ #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_SYNC) ? 0: BDP_ASYNC;
+ ssize_t written = 0, ret;
+ 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))
+ ) {
+ if (pos < i_size_read(inode)) {
+ ret = filemap_write_and_wait_range(mapping, pos, pos + iter->count);
+ if (ret < 0) {
+ goto out;
+ }
+ }
+
+ wbc_attach_fdatawrite_inode(&wbc, mapping->host);
+
+ 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;
+
+ ret = -ENOMEM;
+ folio = netfs_grab_folio_for_write(mapping, pos, part);
+ if (!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(folio));
+ 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)) {
+ ret = netfs_end_writethrough(wreq, iocb);
+ wbc_detach_inode(&wbc);
+ if (ret == -EIOCBQUEUED)
+ return ret;
+ }
+
+ 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 ((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 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;
+
+ /* 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_fdatawait_range(inode->i_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(folio), 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(folio) != index) {
+ xas_reset(xas);
+ break;
+ }
+
+ if (!folio_try_get_rcu(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(folio), 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_rcu(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(folio));
+
+ /* 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);
projects / users / dwmw2 / linux.git / commitdiff