Hi, This is V4 of the patches. Changes from V3 are as follows. This patch series applies on top of Amir's patch to not return -EIO and allows me to create ORIGIN for hardlinks even if index=off. - Got rid of dependency on index=on/off. (Amir) - Re-introduced patch to create ORIGIN for hardlink copy up even if index=off. - Gor rid of helpers around new barriers and open coded these. It will atleast help to see what I am trying to achieve. (Amir). - Got rid of boolean set_size (Amir) - Reorganized some code (Amir) - Renamed ovl_copy_up_data_inode() function. (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 (11): ovl: Create origin xattr on copy up for all files ovl: ovl_check_setxattr() get rid of redundant -EOPNOTSUPP check ovl: During copy up, first copy up metadata and then data ovl: Provide a mount option metacopy=on/off for metadata copyup ovl: Copy up only metadata during copy up where it makes sense ovl: Set xattr OVL_XATTR_METACOPY on upper file ovl: Fix ovl_getattr() to get number of blocks from lower ovl: Set OVL_METACOPY 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: Put barriers to order oi->__upperdentry and OVL_METACOPY update fs/overlayfs/Kconfig | 8 ++++ fs/overlayfs/copy_up.c | 113 ++++++++++++++++++++++++++++++++++++----------- fs/overlayfs/inode.c | 17 ++++++- fs/overlayfs/namei.c | 40 +++++++++++++++++ fs/overlayfs/overlayfs.h | 5 ++- fs/overlayfs/ovl_entry.h | 1 + fs/overlayfs/super.c | 48 ++++++++++++++++++-- fs/overlayfs/util.c | 46 ++++++++++++++----- 8 files changed, 235 insertions(+), 43 deletions(-) -- 2.13.5 -- 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
