block: Don't invalidate pagecache for invalid falloc modes

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>

diff --git a/block/fops.c b/block/fops.c
index acff3d5..73e4274 100644 (file)
--- a/block/fops.c
+++ b/block/fops.c
@@ -772,24 +772,35 @@ static long blkdev_fallocate(struct file *file, int mode, loff_t start,
 
        filemap_invalidate_lock(inode->i_mapping);
 
-       /* Invalidate the page cache, including dirty pages. */
-       error = truncate_bdev_range(bdev, file_to_blk_mode(file), 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_to_blk_mode(file), start, end);
+               if (error)
+                       goto fail;
+
                error = blkdev_issue_zeroout(bdev, start >> SECTOR_SHIFT,
                                             len >> SECTOR_SHIFT, GFP_KERNEL,
                                             BLKDEV_ZERO_NOUNMAP);
                break;
        case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
+               error = truncate_bdev_range(bdev, file_to_blk_mode(file), start, end);
+               if (error)
+                       goto fail;
+
                error = blkdev_issue_zeroout(bdev, start >> SECTOR_SHIFT,
                                             len >> SECTOR_SHIFT, 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_to_blk_mode(file), start, end);
+               if (error)
+                       goto fail;
+
                error = blkdev_issue_discard(bdev, start >> SECTOR_SHIFT,
                                             len >> SECTOR_SHIFT, GFP_KERNEL);
                break;