Welp, time for another patchbomb! As usual, the patchbomb starts with 8 minor bug fixes. The first two add some extra reporting and fix Coverity bugs. Patch 3 adds the ability to create sockets when performing mke2fs -D. Patch 4 changes mke2fs to always complain when formatting inline_data with 128-byte inodes. Patch 5-6 fix some problems when dumping journals in debugfs. Patch 7 fixes a bug in resize2fs when sparse_super2. Patch 8 fixes a bug in mke2fs where block group checksums weren't being set when the user specifies packed metadata blocks. Patch 9 adds an extended option to mke2fs so that users can set the error behavior at format time. Patches 10-14 make some alterations to metadata checksumming support; by default, e2fsck will now check the inode before verifying the checksum. There's a command line option to restore the "just scrape it off the system" behavior for heavily damaged filesystems. There are a couple of patches to fix erroneous behavior and crashes when e2fsck has to rebuild the root directory. The final patch in this clump adds a command line option to dumpe2fs to ignore checksum failures. Patch 15 enables block_validity for new filesystems. As noted here previously, the overhead of enabling this option seems to be at most a 1% performance hit when performing a lot of small allocations, and negligible otherwise. On the plus side, the filesystem is smarter about noticing erroneous allocations out of metadata areas (i.e. block bitmap corruption) and shutting itself down to prevent damage. Patches 16-17 enhance ext2fs_bmap2() to allow the creation of uninitialized extents. The functionality is already there; really it just adds a flag to indicate uninitialized. There's also a patch to the fileio routines to handle uninitialized extents. These patches are unchanged from December. Patches 18-20 add to resize2fs the ability to convert a filesystem to and from 64bit mode. These patches are unchanged from December. Patches 21-24 implement readahead for e2fsck. The first patch tries to reduce system call overhead by using pread/pwrite if available. The next two patches plumb in the IO manager and library changes necessary to read metadata blocks into the page cache (on Linux). The final patch teaches e2fsck to use the library readahead functions in a separate thread. Crude testing has been done via: # echo 3 > /proc/sys/vm/drop_caches # e2fsck -Fnfvtt /dev/XXX So far in my crude testing on a cold system, I've seen about a ~20% speedup on a SSD, a ~40% speedup on a 3x RAID1 SATA array, and about a 10% speedup on a single-spindle SATA disk. On a single-queue USB HDD, performance doesn't change much. It looks as though low end storage like USB HDDs will not benefit, which doesn't surprise me. There's around a 2% regression for USB HDDs, though it doesn't seem statistically significant. The SSD numbers are harder to quantify since they're already fast. Somewhat unexpectedly, the readahead code speeds up e2fsck even when the page cache has already been warmed up. This third version of the readahead patches try to prevent page cache thrashing by limiting the amount of (user-configurable) readahead to a default of half of physical memory. It also tries to release some of the memory pages if it can conclude that it's totally done with a block, and it can now detect very slow readahead and disable it. Patches 25-29 implement fallocate for e2fsprogs, and modifies Ted's mk_hugefiles functionality to use it. The general fallocate API call is (regrettably) much more complex than Ted's, since it must grapple with the possibility that the file already has mapped blocks. There were also a lot of bigalloc related subtleties. Patches 30-33 implement fuse2fs, a FUSE server based on libext2fs. Primarily I've been using it to shake out bugs in the library via xfstests and the metadata checksumming test program. It can also be used to mount ext4 on any OS supporting FUSE, and it can also mount 64k-block filesystems on x86, though I'd be wary of using rw mode. fuse2fs depends on these new APIs: xattr editing, uninit extent handling, and the new fallocate call. Patches 34-36 provide the metadata checksumming test script. Its primary advantage over 'make check' is that it allows one to specify a variety of different mkfs and mount options. It's also growing more tests as a result of fuse2fs exercise. Patch 37 introduces ext5, which reduces our testing matrix by requiring a fairly large set of features and eliminating most mount options. True, not all the features are stable or ready for production yet, but six years after ext4 we have a bunch of new features ready for wider testing. I've tested these e2fsprogs changes against the -next branch as of 4/17. These days, I use several VMs, each with 8GB ramdisks to test with; the test process is checkpatch > make C=1 > make check > metadata checksum tests > fuse + xfstests. Comments and questions are, as always, welcome. --D -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
