Add support for writeback of journalled data directly into
ext4_writepages() instead of offloading it to write_cache_pages(). This
actually significantly simplifies the code and reduces code duplication.
For checkpointing of committed data we can use ext4_writepages()
rightaway the same way as writeback of ordered data uses it on
transaction commit. For journalling of dirty mapped pages, we need to
add a special case to mpage_prepare_extent_to_map() to add all page
buffers to the journal.
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
fs/ext4/inode.c | 340 ++++++++++--------------------------
include/trace/events/ext4.h | 7 -
2 files changed, 90 insertions(+), 257 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index d0102b1c6b27..b1bc4e8db6d8 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -136,7 +136,6 @@ static inline int ext4_begin_ordered_truncate(struct inode *inode,
new_size);
}
-static int __ext4_journalled_writepage(struct page *page, unsigned int len);
static int ext4_meta_trans_blocks(struct inode *inode, int lblocks,
int pextents);
@@ -1632,12 +1631,6 @@ static void ext4_print_free_blocks(struct inode *inode)
return;
}
-static int ext4_bh_delay_or_unwritten(handle_t *handle, struct inode *inode,
- struct buffer_head *bh)
-{
- return (buffer_delay(bh) || buffer_unwritten(bh)) && buffer_dirty(bh);
-}
-
/*
* ext4_insert_delayed_block - adds a delayed block to the extents status
* tree, incrementing the reserved cluster/block
@@ -1870,219 +1863,6 @@ int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
return 0;
}
-static int __ext4_journalled_writepage(struct page *page,
- unsigned int len)
-{
- struct address_space *mapping = page->mapping;
- struct inode *inode = mapping->host;
- handle_t *handle = NULL;
- int ret = 0, err = 0;
- int inline_data = ext4_has_inline_data(inode);
- struct buffer_head *inode_bh = NULL;
- loff_t size;
-
- ClearPageChecked(page);
-
- if (inline_data) {
- BUG_ON(page->index != 0);
- BUG_ON(len > ext4_get_max_inline_size(inode));
- inode_bh = ext4_journalled_write_inline_data(inode, len, page);
- if (inode_bh == NULL)
- goto out;
- }
- /*
- * We need to release the page lock before we start the
- * journal, so grab a reference so the page won't disappear
- * out from under us.
- */
- get_page(page);
- unlock_page(page);
-
- handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,
- ext4_writepage_trans_blocks(inode));
- if (IS_ERR(handle)) {
- ret = PTR_ERR(handle);
- put_page(page);
- goto out_no_pagelock;
- }
- BUG_ON(!ext4_handle_valid(handle));
-
- lock_page(page);
- put_page(page);
- size = i_size_read(inode);
- if (page->mapping != mapping || page_offset(page) > size) {
- /* The page got truncated from under us */
- ext4_journal_stop(handle);
- ret = 0;
- goto out;
- }
-
- if (inline_data) {
- ret = ext4_mark_inode_dirty(handle, inode);
- } else {
- struct buffer_head *page_bufs = page_buffers(page);
-
- if (page->index == size >> PAGE_SHIFT)
- len = size & ~PAGE_MASK;
- else
- len = PAGE_SIZE;
-
- ret = ext4_walk_page_buffers(handle, inode, page_bufs, 0, len,
- NULL, do_journal_get_write_access);
-
- err = ext4_walk_page_buffers(handle, inode, page_bufs, 0, len,
- NULL, write_end_fn);
- }
- if (ret == 0)
- ret = err;
- err = ext4_jbd2_inode_add_write(handle, inode, page_offset(page), len);
- if (ret == 0)
- ret = err;
- EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
- err = ext4_journal_stop(handle);
- if (!ret)
- ret = err;
-
- ext4_set_inode_state(inode, EXT4_STATE_JDATA);
-out:
- unlock_page(page);
-out_no_pagelock:
- brelse(inode_bh);
- return ret;
-}
-
-/*
- * Note that we don't need to start a transaction unless we're journaling data
- * because we should have holes filled from ext4_page_mkwrite(). We even don't
- * need to file the inode to the transaction's list in ordered mode because if
- * we are writing back data added by write(), the inode is already there and if
- * we are writing back data modified via mmap(), no one guarantees in which
- * transaction the data will hit the disk. In case we are journaling data, we
- * cannot start transaction directly because transaction start ranks above page
- * lock so we have to do some magic.
- *
- * This function can get called via...
- * - ext4_writepages after taking page lock (have journal handle)
- * - journal_submit_inode_data_buffers (no journal handle)
- * - shrink_page_list via the kswapd/direct reclaim (no journal handle)
- * - grab_page_cache when doing write_begin (have journal handle)
- *
- * We don't do any block allocation in this function. If we have page with
- * multiple blocks we need to write those buffer_heads that are mapped. This
- * is important for mmaped based write. So if we do with blocksize 1K
- * truncate(f, 1024);
- * a = mmap(f, 0, 4096);
- * a[0] = 'a';
- * truncate(f, 4096);
- * we have in the page first buffer_head mapped via page_mkwrite call back
- * but other buffer_heads would be unmapped but dirty (dirty done via the
- * do_wp_page). So writepage should write the first block. If we modify
- * the mmap area beyond 1024 we will again get a page_fault and the
- * page_mkwrite callback will do the block allocation and mark the
- * buffer_heads mapped.
- *
- * We redirty the page if we have any buffer_heads that is either delay or
- * unwritten in the page.
- *
- * We can get recursively called as show below.
- *
- * ext4_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() ->
- * ext4_writepage()
- *
- * But since we don't do any block allocation we should not deadlock.
- * Page also have the dirty flag cleared so we don't get recurive page_lock.
- */
-static int ext4_writepage(struct page *page,
- struct writeback_control *wbc)
-{
- struct folio *folio = page_folio(page);
- int ret = 0;
- loff_t size;
- unsigned int len;
- struct buffer_head *page_bufs = NULL;
- struct inode *inode = page->mapping->host;
- struct ext4_io_submit io_submit;
-
- if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb)))) {
- folio_invalidate(folio, 0, folio_size(folio));
- folio_unlock(folio);
- return -EIO;
- }
-
- trace_ext4_writepage(page);
- size = i_size_read(inode);
- if (page->index == size >> PAGE_SHIFT &&
- !ext4_verity_in_progress(inode))
- len = size & ~PAGE_MASK;
- else
- len = PAGE_SIZE;
-
- /* Should never happen but for bugs in other kernel subsystems */
- if (!page_has_buffers(page)) {
- ext4_warning_inode(inode,
- "page %lu does not have buffers attached", page->index);
- ClearPageDirty(page);
- unlock_page(page);
- return 0;
- }
-
- page_bufs = page_buffers(page);
- /*
- * We cannot do block allocation or other extent handling in this
- * function. If there are buffers needing that, we have to redirty
- * the page. But we may reach here when we do a journal commit via
- * journal_submit_inode_data_buffers() and in that case we must write
- * allocated buffers to achieve data=ordered mode guarantees.
- *
- * Also, if there is only one buffer per page (the fs block
- * size == the page size), if one buffer needs block
- * allocation or needs to modify the extent tree to clear the
- * unwritten flag, we know that the page can't be written at
- * all, so we might as well refuse the write immediately.
- * Unfortunately if the block size != page size, we can't as
- * easily detect this case using ext4_walk_page_buffers(), but
- * for the extremely common case, this is an optimization that
- * skips a useless round trip through ext4_bio_write_page().
- */
- if (ext4_walk_page_buffers(NULL, inode, page_bufs, 0, len, NULL,
- ext4_bh_delay_or_unwritten)) {
- redirty_page_for_writepage(wbc, page);
- if ((current->flags & PF_MEMALLOC) ||
- (inode->i_sb->s_blocksize == PAGE_SIZE)) {
- /*
- * For memory cleaning there's no point in writing only
- * some buffers. So just bail out. Warn if we came here
- * from direct reclaim.
- */
- WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD))
- == PF_MEMALLOC);
- unlock_page(page);
- return 0;
- }
- }
-
- if (PageChecked(page) && ext4_should_journal_data(inode))
- /*
- * It's mmapped pagecache. Add buffers and journal it. There
- * doesn't seem much point in redirtying the page here.
- */
- return __ext4_journalled_writepage(page, len);
-
- ext4_io_submit_init(&io_submit, wbc);
- io_submit.io_end = ext4_init_io_end(inode, GFP_NOFS);
- if (!io_submit.io_end) {
- redirty_page_for_writepage(wbc, page);
- unlock_page(page);
- return -ENOMEM;
- }
- ret = ext4_bio_write_page(&io_submit, page, len);
- unlock_page(page);
- ext4_io_submit(&io_submit);
- /* Drop io_end reference we got from init */
- ext4_put_io_end_defer(io_submit.io_end);
- return ret;
-}
-
static void mpage_page_done(struct mpage_da_data *mpd, struct page *page)
{
mpd->first_page++;
@@ -2563,6 +2343,50 @@ static bool ext4_page_nomap_can_writeout(struct page *page)
return false;
}
+static int ext4_journal_page_buffers(handle_t *handle, struct page *page,
+ int len)
+{
+ struct buffer_head *page_bufs = page_buffers(page);
+ struct inode *inode = page->mapping->host;
+ int ret, err;
+
+ ret = ext4_walk_page_buffers(handle, inode, page_bufs, 0, len,
+ NULL, do_journal_get_write_access);
+ err = ext4_walk_page_buffers(handle, inode, page_bufs, 0, len,
+ NULL, write_end_fn);
+ if (ret == 0)
+ ret = err;
+ err = ext4_jbd2_inode_add_write(handle, inode, page_offset(page), len);
+ if (ret == 0)
+ ret = err;
+ EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
+
+ ext4_set_inode_state(inode, EXT4_STATE_JDATA);
+
+ return ret;
+}
+
+static int mpage_journal_page_buffers(handle_t *handle,
+ struct mpage_da_data *mpd,
+ struct page *page)
+{
+ struct inode *inode = mpd->inode;
+ loff_t size = i_size_read(inode);
+ int len;
+
+ ClearPageChecked(page);
+ clear_page_dirty_for_io(page);
+ mpd->wbc->nr_to_write--;
+
+ if (page->index == size >> PAGE_SHIFT &&
+ !ext4_verity_in_progress(inode))
+ len = size & ~PAGE_MASK;
+ else
+ len = PAGE_SIZE;
+
+ return ext4_journal_page_buffers(handle, page, len);
+}
+
/*
* mpage_prepare_extent_to_map - find & lock contiguous range of dirty pages
* needing mapping, submit mapped pages
@@ -2595,12 +2419,20 @@ static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd)
int blkbits = mpd->inode->i_blkbits;
ext4_lblk_t lblk;
struct buffer_head *head;
+ handle_t *handle = NULL;
+ int bpp = ext4_journal_blocks_per_page(mpd->inode);
if (mpd->wbc->sync_mode == WB_SYNC_ALL || mpd->wbc->tagged_writepages)
tag = PAGECACHE_TAG_TOWRITE;
else
tag = PAGECACHE_TAG_DIRTY;
+ if (ext4_should_journal_data(mpd->inode)) {
+ handle = ext4_journal_start(mpd->inode, EXT4_HT_WRITE_PAGE,
+ bpp);
+ if (IS_ERR(handle))
+ return PTR_ERR(handle);
+ }
pagevec_init(&pvec);
mpd->map.m_len = 0;
mpd->next_page = index;
@@ -2630,6 +2462,13 @@ static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd)
if (mpd->map.m_len > 0 && mpd->next_page != page->index)
goto out;
+ if (handle) {
+ err = ext4_journal_ensure_credits(handle, bpp,
+ 0);
+ if (err < 0)
+ goto out;
+ }
+
lock_page(page);
/*
* If the page is no longer dirty, or its mapping no
@@ -2669,8 +2508,15 @@ static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd)
mpd->first_page = page->index;
mpd->next_page = page->index + 1;
/*
- * Writeout for transaction commit where we cannot
- * modify metadata is simple. Just submit the page.
+ * Writeout when we cannot modify metadata is simple.
+ * Just submit the page. For data=journal mode we
+ * first handle writeout of the page for checkpoint and
+ * only after that handle delayed page dirtying. This
+ * is crutial so that forcing a transaction commit and
+ * then calling filemap_write_and_wait() guarantees
+ * current state of data is in its final location. Such
+ * sequence is used for example by insert/collapse
+ * range operations before discarding the page cache.
*/
if (!mpd->can_map) {
if (ext4_page_nomap_can_writeout(page)) {
@@ -2678,6 +2524,13 @@ static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd)
if (err < 0)
goto out;
}
+ /* Pending dirtying of journalled data? */
+ if (PageChecked(page)) {
+ err = mpage_journal_page_buffers(handle,
+ mpd, page);
+ if (err < 0)
+ goto out;
+ }
mpage_page_done(mpd, page);
} else {
/* Add all dirty buffers to mpd */
@@ -2695,18 +2548,16 @@ static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd)
cond_resched();
}
mpd->scanned_until_end = 1;
+ if (handle)
+ ext4_journal_stop(handle);
return 0;
out:
pagevec_release(&pvec);
+ if (handle)
+ ext4_journal_stop(handle);
return err;
}
-static int ext4_writepage_cb(struct page *page, struct writeback_control *wbc,
- void *data)
-{
- return ext4_writepage(page, wbc);
-}
-
static int ext4_do_writepages(struct mpage_da_data *mpd)
{
struct writeback_control *wbc = mpd->wbc;
@@ -2732,13 +2583,6 @@ static int ext4_do_writepages(struct mpage_da_data *mpd)
if (!mapping->nrpages || !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
goto out_writepages;
- if (ext4_should_journal_data(inode)) {
- blk_start_plug(&plug);
- ret = write_cache_pages(mapping, wbc, ext4_writepage_cb, NULL);
- blk_finish_plug(&plug);
- goto out_writepages;
- }
-
/*
* If the filesystem has aborted, it is read-only, so return
* right away instead of dumping stack traces later on that
@@ -2773,6 +2617,13 @@ static int ext4_do_writepages(struct mpage_da_data *mpd)
ext4_journal_stop(handle);
}
+ /*
+ * data=journal mode does not do delalloc so we just need to writeout /
+ * journal already mapped buffers
+ */
+ if (ext4_should_journal_data(inode))
+ mpd->can_map = 0;
+
if (ext4_should_dioread_nolock(inode)) {
/*
* We may need to convert up to one extent per block in
@@ -3149,9 +3000,8 @@ static int ext4_da_write_end(struct file *file,
* i_disksize since writeback will push i_disksize upto i_size
* eventually. If the end of the current write is > i_size and
* inside an allocated block (ext4_da_should_update_i_disksize()
- * check), we need to update i_disksize here as neither
- * ext4_writepage() nor certain ext4_writepages() paths not
- * allocating blocks update i_disksize.
+ * check), we need to update i_disksize here as certain
+ * ext4_writepages() paths not allocating blocks update i_disksize.
*
* Note that we defer inode dirtying to generic_write_end() /
* ext4_da_write_inline_data_end().
@@ -5373,7 +5223,7 @@ static void ext4_wait_for_tail_page_commit(struct inode *inode)
* If the folio is fully truncated, we don't need to wait for any commit
* (and we even should not as __ext4_journalled_invalidate_folio() may
* strip all buffers from the folio but keep the folio dirty which can then
- * confuse e.g. concurrent ext4_writepage() seeing dirty folio without
+ * confuse e.g. concurrent ext4_writepages() seeing dirty folio without
* buffers). Also we don't need to wait for any commit if all buffers in
* the folio remain valid. This is most beneficial for the common case of
* blocksize == PAGESIZE.
@@ -6311,18 +6161,8 @@ vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf)
err = __block_write_begin(page, 0, len, ext4_get_block);
if (!err) {
ret = VM_FAULT_SIGBUS;
- if (ext4_walk_page_buffers(handle, inode,
- page_buffers(page), 0, len, NULL,
- do_journal_get_write_access))
- goto out_error;
- if (ext4_walk_page_buffers(handle, inode,
- page_buffers(page), 0, len, NULL,
- write_end_fn))
- goto out_error;
- if (ext4_jbd2_inode_add_write(handle, inode,
- page_offset(page), len))
+ if (ext4_journal_page_buffers(handle, page, len))
goto out_error;
- ext4_set_inode_state(inode, EXT4_STATE_JDATA);
} else {
unlock_page(page);
}
diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h
index 77b426ae0064..ebccf6a6aa1b 100644
--- a/include/trace/events/ext4.h
+++ b/include/trace/events/ext4.h
@@ -584,13 +584,6 @@ DECLARE_EVENT_CLASS(ext4__page_op,
(unsigned long) __entry->index)
);
-DEFINE_EVENT(ext4__page_op, ext4_writepage,
-
- TP_PROTO(struct page *page),
-
- TP_ARGS(page)
-);
-
DEFINE_EVENT(ext4__page_op, ext4_readpage,
TP_PROTO(struct page *page),
--
2.35.3
