Well it's been a while, but this time there aren't as many patches. :) The first two patches provide some minor tweaks to the extended attribute editing code that had been sitting (unreleased :/) in my tree when Ted pulled in v4 of the extended attribute patches. Most notable is a fix for the delete method being unable to remove the last xattr attached to an inode. Patches 3-6 implement various minor bug fixes and cleanups, some of which are based on complaints from clang and cppcheck. Patches 7-8 fix some warts I've noticed while running e2fsck with regards to inline data and printing runs of duplicate blocks. Patches 9-10 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's also a command line option to dumpe2fs to ignore checksum failures. Patch 11 enables block_validity for new filesystems. See patch 30 for a performance microbenchmark. Patches 12-13 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 14-16 add to resize2fs the ability to convert a filesystem to and from 64bit mode. These patches are unchanged from December. Patches 17-20 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 21-25 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 26-29 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 30-32 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. I've tested these e2fsprogs changes against the -next branch as of 3/1. These days, I use an 8GB ramdisk and a 20T "disk" I constructed out of dm-snapshot to test in an x64 VM. The make check tests should pass, and most of the xfstests should pass when run against fuse2fs. 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
