[PATCH 5.15 02/59] block: Dont invalidate pagecache for invalid falloc modes - Greg Kroah-Hartman

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev, "Darrick J. Wong" <djwong@kernel.org>,
	Sarthak Kukreti <sarthakkukreti@chromium.org>,
	Christoph Hellwig <hch@lst.de>, Mike Snitzer <snitzer@kernel.org>,
	Jens Axboe <axboe@kernel.dk>
Subject: [PATCH 5.15 02/59] block: Dont invalidate pagecache for invalid falloc modes
Date: Sat, 13 Jan 2024 10:49:33 +0100	[thread overview]
Message-ID: <20240113094209.383061026@linuxfoundation.org> (raw)
In-Reply-To: <20240113094209.301672391@linuxfoundation.org>

5.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sarthak Kukreti <sarthakkukreti@chromium.org>

commit 1364a3c391aedfeb32aa025303ead3d7c91cdf9d upstream.

Only call truncate_bdev_range() if the fallocate mode is supported. This
fixes a bug where data in the pagecache could be invalidated if the
fallocate() was called on the block device with an invalid mode.

Fixes: 25f4c41415e5 ("block: implement (some of) fallocate for block devices")
Cc: stable@vger.kernel.org
Reported-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Sarthak Kukreti <sarthakkukreti@chromium.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Fixes: line?  I've never seen those wrapped.
Link: https://lore.kernel.org/r/20231011201230.750105-1-sarthakkukreti@chromium.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sarthak Kukreti <sarthakkukreti@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 block/fops.c |   21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

--- a/block/fops.c
+++ b/block/fops.c
@@ -599,22 +599,33 @@ static long blkdev_fallocate(struct file
 
 	filemap_invalidate_lock(inode->i_mapping);
 
-	/* Invalidate the page cache, including dirty pages. */
-	error = truncate_bdev_range(bdev, file->f_mode, start, end);
-	if (error)
-		goto fail;
-
+	/*
+	 * Invalidate the page cache, including dirty pages, for valid
+	 * de-allocate mode calls to fallocate().
+	 */
 	switch (mode) {
 	case FALLOC_FL_ZERO_RANGE:
 	case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
+		error = truncate_bdev_range(bdev, file->f_mode, start, end);
+		if (error)
+			goto fail;
+
 		error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
 					    GFP_KERNEL, BLKDEV_ZERO_NOUNMAP);
 		break;
 	case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
+		error = truncate_bdev_range(bdev, file->f_mode, start, end);
+		if (error)
+			goto fail;
+
 		error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
 					     GFP_KERNEL, BLKDEV_ZERO_NOFALLBACK);
 		break;
 	case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE:
+		error = truncate_bdev_range(bdev, file->f_mode, start, end);
+		if (error)
+			goto fail;
+
 		error = blkdev_issue_discard(bdev, start >> 9, len >> 9,
 					     GFP_KERNEL, 0);
 		break;


