Hi Dave, Please pull this branch with changes for xfs. As usual, I did a test-merge with the main upstream branch as of a few minutes ago, and didn't see any conflicts. Please let me know if you encounter any problems. --D The following changes since commit 4f5e304248ab4939e9aef58244041c194f01f0b5: xfs: cross-reference rmap records with refcount btrees (2023-04-11 19:00:39 -0700) are available in the Git repository at: git://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux.git tags/fix-asciici-bugs-6.4_2023-04-11 for you to fetch changes up to 7ba83850ca2691865713b307ed001bde5fddb084: xfs: deprecate the ascii-ci feature (2023-04-11 19:05:19 -0700) ---------------------------------------------------------------- xfs: fix ascii-ci problems, then kill it [v2] Last week, I was fiddling around with the metadump name obfuscation code while writing a debugger command to generate directories full of names that all have the same hash name. I had a few questions about how well all that worked with ascii-ci mode, and discovered a nasty discrepancy between the kernel and glibc's implementations of the tolower() function. I discovered that I could create a directory that is large enough to require separate leaf index blocks. The hashes stored in the dabtree use the ascii-ci specific hash function, which uses a library function to convert the name to lowercase before hashing. If the kernel and C library's versions of tolower do not behave exactly identically, xfs_ascii_ci_hashname will not produce the same results for the same inputs. xfs_repair will deem the leaf information corrupt and rebuild the directory. After that, lookups in the kernel will fail because the hash index doesn't work. The kernel's tolower function will convert extended ascii uppercase letters (e.g. A-with-umlaut) to extended ascii lowercase letters (e.g. a-with-umlaut), whereas glibc's will only do that if you force LANG to ascii. Tiny embedded libc implementations just plain won't do it at all, and the result is a mess. Stabilize the behavior of the hash function by encoding the name transformation function in libxfs, add it to the selftest, and fix all the userspace tools, none of which handle this transformation correctly. The v1 series generated a /lot/ of discussion, in which several things became very clear: (1) Linus is not enamored of case folding of any kind; (2) Dave and Christoph don't seem to agree on whether the feature is supposed to work for 7-bit ascii or latin1; (3) it trashes UTF8 encoded names if those happen to show up; and (4) I don't want to maintain this mess any longer than I have to. Kill it in 2030. v2: rename the functions to make it clear we're moving away from the letters t, o, l, o, w, e, and r; and deprecate the whole feature once we've fixed the bugs and added tests. Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx> ---------------------------------------------------------------- Darrick J. Wong (3): xfs: stabilize the dirent name transformation function used for ascii-ci dir hash computation xfs: test the ascii case-insensitive hash xfs: deprecate the ascii-ci feature Documentation/admin-guide/xfs.rst | 1 + fs/xfs/Kconfig | 27 +++++ fs/xfs/libxfs/xfs_dir2.c | 5 +- fs/xfs/libxfs/xfs_dir2.h | 31 ++++++ fs/xfs/xfs_dahash_test.c | 211 ++++++++++++++++++++------------------ fs/xfs/xfs_super.c | 13 +++ 6 files changed, 186 insertions(+), 102 deletions(-)
