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@kernel.org>
Link: https://lore.kernel.org/r/20241002150213.GC21853@frogsfrogsfrogs
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/dax.c b/fs/dax.c
index becb4a6920c6aa1fc0aadb909abefbd8dddd866f..c62acd2812f8d4981aaba82acfeaf972f555362a 100644 (file)
--- 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 d46558990279055cb148495a0cfc5c36a92c47d6..e817564e80e010cc3f6d05c6e37024fcc737429b 100644 (file)
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1366,11 +1366,15 @@ 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;