[PATCH] add AOP_TRUNCATED_PAGE, prepend AOP_ to WRITEPAGE_ACTIVATE
readpage(), prepare_write(), and commit_write() callers are updated to understand the special return code AOP_TRUNCATED_PAGE in the style of writepage() and WRITEPAGE_ACTIVATE. AOP_TRUNCATED_PAGE tells the caller that the callee has unlocked the page and that the operation should be tried again with a new page. OCFS2 uses this to detect and work around a lock inversion in its aop methods. There should be no change in behaviour for methods that don't return AOP_TRUNCATED_PAGE. WRITEPAGE_ACTIVATE is also prepended with AOP_ for consistency and they are made enums so that kerneldoc can be used to document their semantics. Signed-off-by: Zach Brown <zach.brown@oracle.com>
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@@ -158,7 +158,7 @@ static int read_pages(struct address_space *mapping, struct file *filp,
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{
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unsigned page_idx;
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struct pagevec lru_pvec;
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int ret = 0;
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int ret;
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if (mapping->a_ops->readpages) {
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ret = mapping->a_ops->readpages(filp, mapping, pages, nr_pages);
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@@ -171,14 +171,17 @@ static int read_pages(struct address_space *mapping, struct file *filp,
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list_del(&page->lru);
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if (!add_to_page_cache(page, mapping,
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page->index, GFP_KERNEL)) {
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mapping->a_ops->readpage(filp, page);
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if (!pagevec_add(&lru_pvec, page))
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__pagevec_lru_add(&lru_pvec);
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} else {
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page_cache_release(page);
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ret = mapping->a_ops->readpage(filp, page);
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if (ret != AOP_TRUNCATED_PAGE) {
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if (!pagevec_add(&lru_pvec, page))
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__pagevec_lru_add(&lru_pvec);
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continue;
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} /* else fall through to release */
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}
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page_cache_release(page);
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}
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pagevec_lru_add(&lru_pvec);
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ret = 0;
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out:
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return ret;
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}
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