Patch "iomap: constrain the file range passed to iomap_file_unshare" has been added to the 6.11-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    iomap: constrain the file range passed to iomap_file_unshare

to the 6.11-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     iomap-constrain-the-file-range-passed-to-iomap_file_.patch
and it can be found in the queue-6.11 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 3199b70a86527d7b575adbe56a4dd95ad8802c32
Author: Darrick J. Wong <djwong@xxxxxxxxxx>
Date:   Wed Oct 2 08:02:13 2024 -0700

    iomap: constrain the file range passed to iomap_file_unshare
    
    [ Upstream commit a311a08a4237241fb5b9d219d3e33346de6e83e0 ]
    
    File contents can only be shared (i.e. reflinked) below EOF, so it makes
    no sense to try to unshare ranges beyond EOF.  Constrain the file range
    parameters here so that we don't have to do that in the callers.
    
    Fixes: 5f4e5752a8a3 ("fs: add iomap_file_dirty")
    Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20241002150213.GC21853@frogsfrogsfrogs
    Reviewed-by: Christoph Hellwig <hch@xxxxxx>
    Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
    Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/dax.c b/fs/dax.c
index becb4a6920c6a..c62acd2812f8d 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1305,11 +1305,15 @@ int dax_file_unshare(struct inode *inode, loff_t pos, loff_t len,
 	struct iomap_iter iter = {
 		.inode		= inode,
 		.pos		= pos,
-		.len		= len,
 		.flags		= IOMAP_WRITE | IOMAP_UNSHARE | IOMAP_DAX,
 	};
+	loff_t size = i_size_read(inode);
 	int ret;
 
+	if (pos < 0 || pos >= size)
+		return 0;
+
+	iter.len = min(len, size - pos);
 	while ((ret = iomap_iter(&iter, ops)) > 0)
 		iter.processed = dax_unshare_iter(&iter);
 	return ret;
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index f420c53d86acc..389de94715b53 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1382,11 +1382,15 @@ iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len,
 	struct iomap_iter iter = {
 		.inode		= inode,
 		.pos		= pos,
-		.len		= len,
 		.flags		= IOMAP_WRITE | IOMAP_UNSHARE,
 	};
+	loff_t size = i_size_read(inode);
 	int ret;
 
+	if (pos < 0 || pos >= size)
+		return 0;
+
+	iter.len = min(len, size - pos);
 	while ((ret = iomap_iter(&iter, ops)) > 0)
 		iter.processed = iomap_unshare_iter(&iter);
 	return ret;