7.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Joanne Koong [ Upstream commit f7585e1ce3418ec282485854b3d8d31c6a961e37 ] __fuse_copy_file_range() clears the destination page cache after the server replies: truncate_inode_pages_range(inode_out->i_mapping, ALIGN_DOWN(pos_out, PAGE_SIZE), ALIGN(pos_out + bytes_copied, PAGE_SIZE) - 1); A server may legitimately reply that it copied nothing, eg if the source file turns out to be shorter than the size the kernel has cached for it. If pos_out is 0 as well, the end of the range is ALIGN(0, PAGE_SIZE) - 1, which is -1. lend is a uoff_t and truncate_inode_pages_range() takes -1 as its end of file sentinel, so rather than clearing nothing it drops every folio in the destination mapping. That is not only a cache drop. truncate_cleanup_folio() calls folio_cancel_dirty(), and fuse_writeback_range() only wrote back [pos_out, pos_out + len - 1], so dirty data elsewhere in the destination file is discarded without ever reaching the server. Skip the call when the server copied nothing, since there is nothing stale to clear in that case. Fixes: 9b46418c40fe ("fuse: copy_file_range should truncate cache") Cc: stable@vger.kernel.org Signed-off-by: Joanne Koong Signed-off-by: Miklos Szeredi Signed-off-by: Sasha Levin --- fs/fuse/file.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/fs/fuse/file.c b/fs/fuse/file.c index b52f5b45646c9..0f2c9404af74a 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -3058,9 +3058,11 @@ static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in, goto out; } - truncate_inode_pages_range(inode_out->i_mapping, - ALIGN_DOWN(pos_out, PAGE_SIZE), - ALIGN(pos_out + bytes_copied, PAGE_SIZE) - 1); + if (bytes_copied) + truncate_inode_pages_range(inode_out->i_mapping, + ALIGN_DOWN(pos_out, PAGE_SIZE), + ALIGN(pos_out + bytes_copied, + PAGE_SIZE) - 1); file_update_time(file_out); fuse_write_update_attr(inode_out, pos_out + bytes_copied, bytes_copied); -- 2.53.0