On Tue, Dec 20, 2016 at 8:17 AM, Amir Goldstein <amir73il@xxxxxxxxx> wrote: > [adding linux-unionfs] > > On Mon, Dec 19, 2016 at 11:55 PM, Darrick J. Wong > <darrick.wong@xxxxxxxxxx> wrote: >> On Mon, Dec 19, 2016 at 10:11:08PM +0200, Amir Goldstein wrote: >>> deduplicate the xfs file type conversion implementation. >>> >>> xfs readdir code may expose DT_WHT type to user if that >>> type was set on disk, but xfs code never set a file type >>> of WHT on disk. >>> >>> If it is acceptable to expose to user DT_UNKNOWN in case >>> WHT type somehow got to disk, then xfs_dir3_filetype_table >>> could also be replaced with the common fs_dtype() helper. >> >> AFAIK XFS has never actually written XFS_DIR3_FT_WHT to disk. >> I see that overlayfs whiteouts are now some sort of weird >> chardev with rdev == 0, so I guess overlayfs doesn't either...? >> > > Nope. overlayfs calls vfs_whiteout() which calls i_op->mknod(.. S_IFCHR, 0) > So AFAIK, there is no evidence of DT_WHT even being use in Linux. > > From overlayfs perspective, it could have been nice if conversion functions > took mode+rdev instead of just mode and produced the DT_WHT value, > but it is not all that easy to know how applications would react to this change. > > I suppose there shouldn't be a problem to expose DT_WHT d_type in > iterate_dir() and convert it to DT_CHR in getdents' filldir(). > It will be beneficial to overlayfs in case of a directory with tons of > whiteouts, > not having to stat all those inodes is a big win. > Not sure how common this use case is, but it is quite easy for users to > get to this sort of state when using inefficient container layouts. > > How about xfs_repair? will it complain if it sees DT_WHT and a chardev > inode? does it check at all that the type and mode match? > To answer my own question, yes, xfs_repair would complain and fix this, so not possible to set DT_WHT type for the VFS whiteout creature without adding a new feature flag. Amir. -- 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
