From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4F62E3A1BA; Tue, 9 Jan 2024 14:34:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="ToQx4GGb" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=cca0/i33EOqMAkZgYIeSRXbVYWRM3R2G+zhbkmE3gJs=; b=ToQx4GGbYUyKYdHFRtG64tsI0E 6B1SLA7rgJoaFg6yV275YZFQodqDN4YazJdaRo6sLRwxzDy+THnFq1skLIjawWPpwu0hrC80kO/GT PWfsA1BBnWCOtaLvsiwJiOSxT6322c9oa9kxga1dOg6iPY9KxKXcoXNvM2rx3qltZuujcRUBee3cm WN8eN2/Em1DgWFgGc+JBEFB67pyM4zUNj/i1Pj2pFnRJ4zYGv1dANBmydKmytpTwYqbHxzOcbEBPt sXFER4VtTGWV3dXlqTRq8me73WxnozzI9kQzq82DU8D7t8UOsME8o4brJ1Sh/kqO9Thtxi132IRaS Rmjiyl6g==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1rNDB1-009xrU-0M; Tue, 09 Jan 2024 14:33:59 +0000 From: "Matthew Wilcox (Oracle)" To: Jonathan Corbet Cc: "Matthew Wilcox (Oracle)" , linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 3/8] buffer: Add kernel-doc for try_to_free_buffers() Date: Tue, 9 Jan 2024 14:33:52 +0000 Message-Id: <20240109143357.2375046-4-willy@infradead.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20240109143357.2375046-1-willy@infradead.org> References: <20240109143357.2375046-1-willy@infradead.org> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The documentation for this function has become separated from it over time; move it to the right place and turn it into kernel-doc. Mild editing of the content to make it more about what the function does, and less about how it does it. Signed-off-by: Matthew Wilcox (Oracle) --- fs/buffer.c | 44 ++++++++++++++++++++++++-------------------- 1 file changed, 24 insertions(+), 20 deletions(-) diff --git a/fs/buffer.c b/fs/buffer.c index 071f01b28c90..25861241657f 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -2864,26 +2864,6 @@ int sync_dirty_buffer(struct buffer_head *bh) } EXPORT_SYMBOL(sync_dirty_buffer); -/* - * try_to_free_buffers() checks if all the buffers on this particular folio - * are unused, and releases them if so. - * - * Exclusion against try_to_free_buffers may be obtained by either - * locking the folio or by holding its mapping's i_private_lock. - * - * If the folio is dirty but all the buffers are clean then we need to - * be sure to mark the folio clean as well. This is because the folio - * may be against a block device, and a later reattachment of buffers - * to a dirty folio will set *all* buffers dirty. Which would corrupt - * filesystem data on the same device. - * - * The same applies to regular filesystem folios: if all the buffers are - * clean then we set the folio clean and proceed. To do that, we require - * total exclusion from block_dirty_folio(). That is obtained with - * i_private_lock. - * - * try_to_free_buffers() is non-blocking. - */ static inline int buffer_busy(struct buffer_head *bh) { return atomic_read(&bh->b_count) | @@ -2917,6 +2897,30 @@ drop_buffers(struct folio *folio, struct buffer_head **buffers_to_free) return false; } +/** + * try_to_free_buffers: Release buffers attached to this folio. + * @folio: The folio. + * + * If any buffers are in use (dirty, under writeback, elevated refcount), + * no buffers will be freed. + * + * If the folio is dirty but all the buffers are clean then we need to + * be sure to mark the folio clean as well. This is because the folio + * may be against a block device, and a later reattachment of buffers + * to a dirty folio will set *all* buffers dirty. Which would corrupt + * filesystem data on the same device. + * + * The same applies to regular filesystem folios: if all the buffers are + * clean then we set the folio clean and proceed. To do that, we require + * total exclusion from block_dirty_folio(). That is obtained with + * i_private_lock. + * + * Exclusion against try_to_free_buffers may be obtained by either + * locking the folio or by holding its mapping's i_private_lock. + * + * Context: Process context. @folio must be locked. Will not sleep. + * Return: true if all buffers attached to this folio were freed. + */ bool try_to_free_buffers(struct folio *folio) { struct address_space * const mapping = folio->mapping; -- 2.43.0