Hi, Here is the V5 of patches. Following are changes from V4. - Flipped the meaning of bit. Now OVL_METACOPY is called OVL_UPPERDATA and dropped a barrier patch which implemented ordering requirements between oi->flags and oi->__upperdentry. - Now ovl_d_real() does return upper dentry if upper dentry is metacopy only dentry. - Added a fix to ovl_lookup() goto statement. - Renamed ->metadata_only to ->metacopy - Replaced BUG_ON() with WARN_ON() in ovl_copy_up_meta_inode_data() - Added WARN_ON(!OVL_TYPE_ORIGIN(type)) in ovl_getattr() - Took care of bunch of code organization comments from Amir. Original Description -------------------- In one of the recent converstions, people mentioned that chown/chmod lead to copy up files as well as data. We could optimize it so that only metadata is copied up during chown/chmod and data is copied up when file is opened for WRITE. This optimization potentially could be useful with containers and user namespaces. In popular scenario, people end up doing chown() on whole image directory tree based on container mappings. And this chown copies up everything, breaking sharing of page cache between containers. With these patches, only metadat is copied up during chown() and if file is opened for READ, d_real() returns lower dentry/inode. That way, different containers can still continue to use page cache. That's the use case I have in mind. Basically, I am relying on storing OVL_XATTR_ORIGIN in upper inode during copy up. I use that information to get to lower inode later and do data copy up when necessary. I also store OVL_XATTR_METACOPY in upper inode to mark that only metadata has been copied up and data copy up still might be required. Any feedback is helpful. Thanks Vivek Vivek Goyal (13): ovl: Put upperdentry if ovl_check_origin() fails ovl: Create origin xattr on copy up for all files ovl: ovl_check_setxattr() get rid of redundant -EOPNOTSUPP check ovl: Provide a mount option metacopy=on/off for metadata copyup ovl: During copy up, first copy up metadata and then data ovl: Copy up only metadata during copy up where it makes sense ovl: A new xattr OVL_XATTR_METACOPY for file on upper ovl: Fix ovl_getattr() to get number of blocks from lower ovl: Set OVL_UPPERDATA flag during ovl_lookup() ovl: Return lower dentry if only metadata copy up took place ovl: Introduce read/write barriers around metacopy flag update ovl: Do not export metacopy only upper dentry ovl: Enable metadata only feature fs/overlayfs/Kconfig | 8 ++++ fs/overlayfs/copy_up.c | 116 +++++++++++++++++++++++++++++++++++------------ fs/overlayfs/inode.c | 15 +++++- fs/overlayfs/namei.c | 38 +++++++++++++++- fs/overlayfs/overlayfs.h | 6 ++- fs/overlayfs/ovl_entry.h | 1 + fs/overlayfs/super.c | 67 +++++++++++++++++++++++++-- fs/overlayfs/util.c | 54 +++++++++++++++++----- 8 files changed, 257 insertions(+), 48 deletions(-) -- 2.5.5 -- To unsubscribe from this list: send the line "unsubscribe linux-unionfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
