[PATCH v5-fix 1/5] block: Don't invalidate pagecache for invalid falloc modes

Sarthak Kukreti
2023-04-20T17:28:34Z

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>
---
block/fops.c | 21 ++++++++++++++++-----
1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/block/fops.c b/block/fops.c
index d2e6be4e3d1c..20b1eddcbe25 100644
--- a/block/fops.c
+++ b/block/fops.c
@@ -648,24 +648,35 @@ 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->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 >> 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->f_mode, 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->f_mode, start, end);
+ if (!error)
+ goto fail;
+
error = blkdev_issue_discard(bdev, start >> SECTOR_SHIFT,
len >> SECTOR_SHIFT, GFP_KERNEL);
break;
--
2.40.0.396.gfff15efe05-goog