Hi, This series aims to deprecate the ->bmap interface, by using FIEMAP infra-structure to handle FIBMAP calls. It doesn't change the FIBMAP api, so the implementation is supposed to be transparent for users. Although this patchset is working as I expected and it survived a few xfstests runs, I have some questions about the way I implemented it that I'd like to discuss, so, I'm tagging it as RFC. The first patch is relatively simple, just replacing direct ->bmap calls by bmap() function (as suggested by Dave Chinner), the second patch actually changes bmap() function to call ->fiemap when available, falling back to ->bmap when ->fiemap isn't implemented. So, in a (hopefully) not so far future, we can get rid of the whole ->bmap interface. These are the main points where I've doubts about: I implemented it reutilizing the same infra-structure used by userspace FIEMAP calls to avoid code duplication if possible, the problem is, to setup the struct fiemap_extent_info to pass it to ->fiemap, I need to use (__force) casting, so the compiler doesn't complain about the "struct fiemap_extent __user *fi_extents_start" into it. I saw a few other places in kernel doing something similar, so, that's why I thought it would be ok to use such strategy. I added a new FIEMAP flag (FIEMAP_KERNEL_FIBMAP), to signal the ->fiemap call is supposed to be internal only and fiemap_fill_next_extent() can do a simple memcpy() instead of a copy_to_user(). I added this flag to include/uapi, but I suppose kernel only flags are not supposed to be in uapi, so, suggestions to where I could place it are welcome. Different filesystems will answer FIEMAP calls in slightly different ways. when the requested range is somewhere in the middle of the extent, some filesystems will set the map starting at the beginning of the extent (like ext4 for example), and some (the ones based on iomap for example), will set the map starting at the offset requested. So, to comply with both cases, bmap() checks the logical offset returned by the filesystem, and take the appropriate action if the filesystem returns the beginning of the extent, or not. What you guys think? Cheers. Carlos Maiolino (2): fs: Replace direct ->bmap calls by bmap() Use fiemap internal infra-structure to handle FIBMAP fs/cachefiles/rdwr.c | 5 ++--- fs/ecryptfs/mmap.c | 5 ++--- fs/inode.c | 38 +++++++++++++++++++++++++++++++++++++- fs/ioctl.c | 25 +++++++++++++++++-------- include/uapi/linux/fiemap.h | 1 + 5 files changed, 59 insertions(+), 15 deletions(-) -- 2.14.4
