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From: Goldwyn Rodrigues <rgoldwyn@suse.de>
To: axboe@kernel.dk
Cc: viro@ZenIV.linux.org.uk, hch@lst.de, jack@suse.cz,
	akpm@linux-foundation.org, linux-block@vger.kernel.org,
	Goldwyn Rodrigues <rgoldwyn@suse.com>
Subject: [PATCH 02/10] fs: Introduce filemap_range_has_page()
Date: Mon, 19 Jun 2017 11:33:40 -0500	[thread overview]
Message-ID: <20170619163348.15542-3-rgoldwyn@suse.de> (raw)
In-Reply-To: <20170619163348.15542-1-rgoldwyn@suse.de>

From: Goldwyn Rodrigues <rgoldwyn@suse.com>

filemap_range_has_page() return true if the file's mapping has
a page within the range mentioned. This function will be used
to check if a write() call will cause a writeback of previous
writes.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
---
 include/linux/fs.h |  2 ++
 mm/filemap.c       | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 96a1a1fa54a9..0d34f5b5a6b0 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2518,6 +2518,8 @@ extern int filemap_fdatawait(struct address_space *);
 extern void filemap_fdatawait_keep_errors(struct address_space *);
 extern int filemap_fdatawait_range(struct address_space *, loff_t lstart,
 				   loff_t lend);
+extern bool filemap_range_has_page(struct address_space *, loff_t lstart,
+				  loff_t lend);
 extern int filemap_write_and_wait(struct address_space *mapping);
 extern int filemap_write_and_wait_range(struct address_space *mapping,
 				        loff_t lstart, loff_t lend);
diff --git a/mm/filemap.c b/mm/filemap.c
index 6f1be573a5e6..9b39a2390b9e 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -376,6 +376,38 @@ int filemap_flush(struct address_space *mapping)
 }
 EXPORT_SYMBOL(filemap_flush);
 
+/**
+ * filemap_range_has_page - check if a page exists in range.
+ * @mapping:           address space within which to check
+ * @start_byte:        offset in bytes where the range starts
+ * @end_byte:          offset in bytes where the range ends (inclusive)
+ *
+ * Find at least one page in the range supplied, usually used to check if
+ * direct writing in this range will trigger a writeback.
+ */
+bool filemap_range_has_page(struct address_space *mapping,
+			   loff_t start_byte, loff_t end_byte)
+{
+	pgoff_t index = start_byte >> PAGE_SHIFT;
+	pgoff_t end = end_byte >> PAGE_SHIFT;
+	struct pagevec pvec;
+	bool ret;
+
+	if (end_byte < start_byte)
+		return false;
+
+	if (mapping->nrpages == 0)
+		return false;
+
+	pagevec_init(&pvec, 0);
+	if (!pagevec_lookup(&pvec, mapping, index, 1))
+		return false;
+	ret = (pvec.pages[0]->index <= end);
+	pagevec_release(&pvec);
+	return ret;
+}
+EXPORT_SYMBOL(filemap_range_has_page);
+
 static int __filemap_fdatawait_range(struct address_space *mapping,
 				     loff_t start_byte, loff_t end_byte)
 {
-- 
2.12.0

  parent reply	other threads:[~2017-06-19 16:33 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-19 16:33 [PATCH 0/10 v13] merge request: No wait AIO Goldwyn Rodrigues
2017-06-19 16:33 ` [PATCH 01/10] fs: Separate out kiocb flags setup based on RWF_* flags Goldwyn Rodrigues
2017-06-19 16:33 ` Goldwyn Rodrigues [this message]
2017-06-19 16:33 ` [PATCH 03/10] fs: Use RWF_* flags for AIO operations Goldwyn Rodrigues
2017-06-19 16:33 ` [PATCH 04/10] fs: Introduce RWF_NOWAIT and FMODE_AIO_NOWAIT Goldwyn Rodrigues
2017-06-19 16:33 ` [PATCH 05/10] fs: return if direct I/O will trigger writeback Goldwyn Rodrigues
2017-06-19 16:44   ` Al Viro
2017-06-19 16:33 ` [PATCH 06/10] fs: Introduce IOMAP_NOWAIT Goldwyn Rodrigues
2017-06-19 16:33 ` [PATCH 07/10] block: return on congested block device Goldwyn Rodrigues
2017-06-19 16:33 ` [PATCH 08/10] ext4: nowait aio support Goldwyn Rodrigues
2017-06-19 16:33 ` [PATCH 09/10] xfs: " Goldwyn Rodrigues
2017-06-19 16:33 ` [PATCH 10/10] btrfs: " Goldwyn Rodrigues
2017-06-19 23:15 ` [PATCH 0/10 v13] merge request: No wait AIO Jens Axboe
2017-06-19 23:20   ` Goldwyn Rodrigues
2017-06-19 23:34   ` Al Viro
2017-06-19 23:36     ` Jens Axboe
2017-06-20  0:24       ` Al Viro
2017-06-20  7:20         ` Christoph Hellwig
2017-06-20 11:53           ` Goldwyn Rodrigues
  -- strict thread matches above, loose matches on Subject: below --
2017-06-20 12:05 [PATCH 0/10 v14] " Goldwyn Rodrigues
2017-06-20 12:05 ` [PATCH 02/10] fs: Introduce filemap_range_has_page() Goldwyn Rodrigues
2017-06-15 15:59 [PATCH 0/10 v12] No wait AIO Goldwyn Rodrigues
2017-06-15 15:59 ` [PATCH 02/10] fs: Introduce filemap_range_has_page() Goldwyn Rodrigues
2017-06-15 18:25   ` Andrew Morton
2017-06-15 18:25     ` Andrew Morton
2017-06-06 11:19 [PATCH 0/10 v11] No wait AIO Goldwyn Rodrigues
2017-06-06 11:19 ` [PATCH 02/10] fs: Introduce filemap_range_has_page() Goldwyn Rodrigues
2017-06-05  5:35 [PATCH 0/10 v10] No wait AIO Goldwyn Rodrigues
2017-06-05  5:35 ` [PATCH 02/10] fs: Introduce filemap_range_has_page() Goldwyn Rodrigues
2017-05-24 16:41 [PATCH 0/10 v9] No wait AIO Goldwyn Rodrigues
2017-05-24 16:41 ` [PATCH 02/10] fs: Introduce filemap_range_has_page() Goldwyn Rodrigues
2017-05-25  8:25   ` Jan Kara
2017-05-11 19:17 [PATCH 0/10 v8] No wait AIO Goldwyn Rodrigues
2017-05-11 19:17 ` [PATCH 02/10] fs: Introduce filemap_range_has_page() Goldwyn Rodrigues

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