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writeback: rework the loop termination condition in write_cache_pages
Rework the way we deal with the cleanup after the writepage call. First handle the magic AOP_WRITEPAGE_ACTIVATE separately from real error returns to get it out of the way of the actual error handling path. The split the handling on intgrity vs non-integrity branches first, and return early using a goto for the non-ingegrity early loop condition to remove the need for the done and done_index local variables, and for assigning the error to ret when we can just return error directly. Link: https://lkml.kernel.org/r/20240215063649.2164017-7-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Christian Brauner <brauner@kernel.org> Cc: Dave Chinner <dchinner@redhat.com> Cc: David Howells <dhowells@redhat.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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@ -2396,13 +2396,12 @@ int write_cache_pages(struct address_space *mapping,
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void *data)
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{
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int ret = 0;
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int done = 0;
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int error;
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struct folio_batch fbatch;
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struct folio *folio;
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int nr_folios;
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pgoff_t index;
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pgoff_t end; /* Inclusive */
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pgoff_t done_index;
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xa_mark_t tag;
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folio_batch_init(&fbatch);
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@ -2419,8 +2418,7 @@ int write_cache_pages(struct address_space *mapping,
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} else {
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tag = PAGECACHE_TAG_DIRTY;
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}
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done_index = index;
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while (!done && (index <= end)) {
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while (index <= end) {
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int i;
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nr_folios = filemap_get_folios_tag(mapping, &index, end,
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@ -2430,11 +2428,7 @@ int write_cache_pages(struct address_space *mapping,
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break;
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for (i = 0; i < nr_folios; i++) {
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struct folio *folio = fbatch.folios[i];
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unsigned long nr;
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done_index = folio->index;
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folio = fbatch.folios[i];
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folio_lock(folio);
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/*
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@ -2469,45 +2463,32 @@ int write_cache_pages(struct address_space *mapping,
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trace_wbc_writepage(wbc, inode_to_bdi(mapping->host));
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error = writepage(folio, wbc, data);
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nr = folio_nr_pages(folio);
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wbc->nr_to_write -= nr;
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if (unlikely(error)) {
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/*
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* Handle errors according to the type of
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* writeback. There's no need to continue for
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* background writeback. Just push done_index
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* past this page so media errors won't choke
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* writeout for the entire file. For integrity
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* writeback, we must process the entire dirty
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* set regardless of errors because the fs may
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* still have state to clear for each page. In
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* that case we continue processing and return
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* the first error.
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*/
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if (error == AOP_WRITEPAGE_ACTIVATE) {
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folio_unlock(folio);
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error = 0;
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} else if (wbc->sync_mode != WB_SYNC_ALL) {
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ret = error;
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done_index = folio->index + nr;
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done = 1;
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break;
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}
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if (!ret)
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ret = error;
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wbc->nr_to_write -= folio_nr_pages(folio);
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if (error == AOP_WRITEPAGE_ACTIVATE) {
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folio_unlock(folio);
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error = 0;
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}
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/*
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* We stop writing back only if we are not doing
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* integrity sync. In case of integrity sync we have to
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* keep going until we have written all the pages
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* we tagged for writeback prior to entering this loop.
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* For integrity writeback we have to keep going until
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* we have written all the folios we tagged for
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* writeback above, even if we run past wbc->nr_to_write
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* or encounter errors.
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* We stash away the first error we encounter in
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* wbc->saved_err so that it can be retrieved when we're
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* done. This is because the file system may still have
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* state to clear for each folio.
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*
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* For background writeback we exit as soon as we run
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* past wbc->nr_to_write or encounter the first error.
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*/
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done_index = folio->index + nr;
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if (wbc->nr_to_write <= 0 &&
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wbc->sync_mode == WB_SYNC_NONE) {
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done = 1;
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break;
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if (wbc->sync_mode == WB_SYNC_ALL) {
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if (error && !ret)
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ret = error;
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} else {
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if (error || wbc->nr_to_write <= 0)
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goto done;
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}
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}
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folio_batch_release(&fbatch);
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@ -2524,14 +2505,15 @@ int write_cache_pages(struct address_space *mapping,
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* of the file if we are called again, which can only happen due to
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* -ENOMEM from the file system.
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*/
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if (wbc->range_cyclic) {
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if (done)
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mapping->writeback_index = done_index;
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else
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mapping->writeback_index = 0;
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}
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if (wbc->range_cyclic)
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mapping->writeback_index = 0;
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return ret;
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done:
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if (wbc->range_cyclic)
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mapping->writeback_index = folio->index + folio_nr_pages(folio);
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folio_batch_release(&fbatch);
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return error;
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}
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EXPORT_SYMBOL(write_cache_pages);
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