linux/fs/ext4/ialloc.c, branch v5.3

ext4: Support case-insensitive file name lookups

2019-04-25T18:12:08Z

This patch implements the actual support for case-insensitive file name lookups in ext4, based on the feature bit and the encoding stored in the superblock. A filesystem that has the casefold feature set is able to configure directories with the +F (EXT4_CASEFOLD_FL) attribute, enabling lookups to succeed in that directory in a case-insensitive fashion, i.e: match a directory entry even if the name used by userspace is not a byte per byte match with the disk name, but is an equivalent case-insensitive version of the Unicode string. This operation is called a case-insensitive file name lookup. The feature is configured as an inode attribute applied to directories and inherited by its children. This attribute can only be enabled on empty directories for filesystems that support the encoding feature, thus preventing collision of file names that only differ by case. * dcache handling: For a +F directory, Ext4 only stores the first equivalent name dentry used in the dcache. This is done to prevent unintentional duplication of dentries in the dcache, while also allowing the VFS code to quickly find the right entry in the cache despite which equivalent string was used in a previous lookup, without having to resort to ->lookup(). d_hash() of casefolded directories is implemented as the hash of the casefolded string, such that we always have a well-known bucket for all the equivalencies of the same string. d_compare() uses the utf8_strncasecmp() infrastructure, which handles the comparison of equivalent, same case, names as well. For now, negative lookups are not inserted in the dcache, since they would need to be invalidated anyway, because we can't trust missing file dentries. This is bad for performance but requires some leveraging of the vfs layer to fix. We can live without that for now, and so does everyone else. * on-disk data: Despite using a specific version of the name as the internal representation within the dcache, the name stored and fetched from the disk is a byte-per-byte match with what the user requested, making this implementation 'name-preserving'. i.e. no actual information is lost when writing to storage. DX is supported by modifying the hashes used in +F directories to make them case/encoding-aware. The new disk hashes are calculated as the hash of the full casefolded string, instead of the string directly. This allows us to efficiently search for file names in the htree without requiring the user to provide an exact name. * Dealing with invalid sequences: By default, when a invalid UTF-8 sequence is identified, ext4 will treat it as an opaque byte sequence, ignoring the encoding and reverting to the old behavior for that unique file. This means that case-insensitive file name lookup will not work only for that file. An optional bit can be set in the superblock telling the filesystem code and userspace tools to enforce the encoding. When that optional bit is set, any attempt to create a file name using an invalid UTF-8 sequence will fail and return an error to userspace. * Normalization algorithm: The UTF-8 algorithms used to compare strings in ext4 is implemented lives in fs/unicode, and is based on a previous version developed by SGI. It implements the Canonical decomposition (NFD) algorithm described by the Unicode specification 12.1, or higher, combined with the elimination of ignorable code points (NFDi) and full case-folding (CF) as documented in fs/unicode/utf8_norm.c. NFD seems to be the best normalization method for EXT4 because: - It has a lower cost than NFC/NFKC (which requires decomposing to NFD as an intermediary step) - It doesn't eliminate important semantic meaning like compatibility decompositions. Although: - This implementation is not completely linguistic accurate, because different languages have conflicting rules, which would require the specialization of the filesystem to a given locale, which brings all sorts of problems for removable media and for users who use more than one language. Signed-off-by: Gabriel Krisman Bertazi Signed-off-by: Theodore Ts'o

ext4: use IS_ENCRYPTED() to check encryption status

2019-01-24T04:56:43Z

This commit removes the ext4 specific ext4_encrypted_inode() and makes use of the generic IS_ENCRYPTED() macro to check for the encryption status of an inode. Reviewed-by: Eric Biggers Signed-off-by: Chandan Rajendra Signed-off-by: Eric Biggers

ext4: avoid declaring fs inconsistent due to invalid file handles

2018-12-19T17:29:13Z

If we receive a file handle, either from NFS or open_by_handle_at(2), and it points at an inode which has not been initialized, and the file system has metadata checksums enabled, we shouldn't try to get the inode, discover the checksum is invalid, and then declare the file system as being inconsistent. This can be reproduced by creating a test file system via "mke2fs -t ext4 -O metadata_csum /tmp/foo.img 8M", mounting it, cd'ing into that directory, and then running the following program. #define _GNU_SOURCE #include struct handle { struct file_handle fh; unsigned char fid[MAX_HANDLE_SZ]; }; int main(int argc, char **argv) { struct handle h = {{8, 1 }, { 12, }}; open_by_handle_at(AT_FDCWD, &h.fh, O_RDONLY); return 0; } Google-Bug-Id: 120690101 Signed-off-by: Theodore Ts'o Cc: stable@kernel.org

ext4: don't open-code ERR_CAST

2018-10-10T20:41:40Z

Signed-off-by: Al Viro

ext4: use ext4_warning() for sb_getblk failure

2018-08-01T16:02:31Z

Out of memory should not be considered as critical errors; so replace ext4_error() with ext4_warnig(). Signed-off-by: Wang Shilong Signed-off-by: Theodore Ts'o Cc: stable@vger.kernel.org

ext4: use timespec64 for all inode times

2018-07-29T19:51:00Z

This is the last missing piece for the inode times on 32-bit systems: now that VFS interfaces use timespec64, we just need to stop truncating the tv_sec values for y2038 compatibililty. Reviewed-by: Andreas Dilger Signed-off-by: Arnd Bergmann Signed-off-by: Theodore Ts'o

ext4: fix check to prevent initializing reserved inodes

2018-07-29T19:34:00Z

Commit 8844618d8aa7: "ext4: only look at the bg_flags field if it is valid" will complain if block group zero does not have the EXT4_BG_INODE_ZEROED flag set. Unfortunately, this is not correct, since a freshly created file system has this flag cleared. It gets almost immediately after the file system is mounted read-write --- but the following somewhat unlikely sequence will end up triggering a false positive report of a corrupted file system: mkfs.ext4 /dev/vdc mount -o ro /dev/vdc /vdc mount -o remount,rw /dev/vdc Instead, when initializing the inode table for block group zero, test to make sure that itable_unused count is not too large, since that is the case that will result in some or all of the reserved inodes getting cleared. This fixes the failures reported by Eric Whiteney when running generic/230 and generic/231 in the the nojournal test case. Fixes: 8844618d8aa7 ("ext4: only look at the bg_flags field if it is valid") Reported-by: Eric Whitney Signed-off-by: Theodore Ts'o

ext4: check for allocation block validity with block group locked

2018-07-12T23:08:05Z

With commit 044e6e3d74a3: "ext4: don't update checksum of new initialized bitmaps" the buffer valid bit will get set without actually setting up the checksum for the allocation bitmap, since the checksum will get calculated once we actually allocate an inode or block. If we are doing this, then we need to (re-)check the verified bit after we take the block group lock. Otherwise, we could race with another process reading and verifying the bitmap, which would then complain about the checksum being invalid. https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1780137 Signed-off-by: Theodore Ts'o Cc: stable@kernel.org

Merge tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

2018-07-08T18:10:30Z

Pull ext4 bugfixes from Ted Ts'o: "Bug fixes for ext4; most of which relate to vulnerabilities where a maliciously crafted file system image can result in a kernel OOPS or hang. At least one fix addresses an inline data bug could be triggered by userspace without the need of a crafted file system (although it does require that the inline data feature be enabled)" * tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: ext4: check superblock mapped prior to committing ext4: add more mount time checks of the superblock ext4: add more inode number paranoia checks ext4: avoid running out of journal credits when appending to an inline file jbd2: don't mark block as modified if the handle is out of credits ext4: never move the system.data xattr out of the inode body ext4: clear i_data in ext4_inode_info when removing inline data ext4: include the illegal physical block in the bad map ext4_error msg ext4: verify the depth of extent tree in ext4_find_extent() ext4: only look at the bg_flags field if it is valid ext4: make sure bitmaps and the inode table don't overlap with bg descriptors ext4: always check block group bounds in ext4_init_block_bitmap() ext4: always verify the magic number in xattr blocks ext4: add corruption check in ext4_xattr_set_entry() ext4: add warn_on_error mount option

Merge tag 'vfs-timespec64' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground

2018-06-14T22:31:07Z

Pull inode timestamps conversion to timespec64 from Arnd Bergmann: "This is a late set of changes from Deepa Dinamani doing an automated treewide conversion of the inode and iattr structures from 'timespec' to 'timespec64', to push the conversion from the VFS layer into the individual file systems. As Deepa writes: 'The series aims to switch vfs timestamps to use struct timespec64. Currently vfs uses struct timespec, which is not y2038 safe. The series involves the following: 1. Add vfs helper functions for supporting struct timepec64 timestamps. 2. Cast prints of vfs timestamps to avoid warnings after the switch. 3. Simplify code using vfs timestamps so that the actual replacement becomes easy. 4. Convert vfs timestamps to use struct timespec64 using a script. This is a flag day patch. Next steps: 1. Convert APIs that can handle timespec64, instead of converting timestamps at the boundaries. 2. Update internal data structures to avoid timestamp conversions' Thomas Gleixner adds: 'I think there is no point to drag that out for the next merge window. The whole thing needs to be done in one go for the core changes which means that you're going to play that catchup game forever. Let's get over with it towards the end of the merge window'" * tag 'vfs-timespec64' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground: pstore: Remove bogus format string definition vfs: change inode times to use struct timespec64 pstore: Convert internal records to timespec64 udf: Simplify calls to udf_disk_stamp_to_time fs: nfs: get rid of memcpys for inode times ceph: make inode time prints to be long long lustre: Use long long type to print inode time fs: add timespec64_truncate()