linux/fs/ext3/dir.c

522 lines
13 KiB

[PATCH] ext3_get_blocks: Mapping multiple blocks at a once Currently ext3_get_block() only maps or allocates one block at a time. This is quite inefficient for sequential IO workload. I have posted a early implements a simply multiple block map and allocation with current ext3. The basic idea is allocating the 1st block in the existing way, and attempting to allocate the next adjacent blocks on a best effort basis. More description about the implementation could be found here: http://marc.theaimsgroup.com/?l=ext2-devel&m=112162230003522&w=2 The following the latest version of the patch: break the original patch into 5 patches, re-worked some logicals, and fixed some bugs. The break ups are: [patch 1] Adding map multiple blocks at a time in ext3_get_blocks() [patch 2] Extend ext3_get_blocks() to support multiple block allocation [patch 3] Implement multiple block allocation in ext3-try-to-allocate (called via ext3_new_block()). [patch 4] Proper accounting updates in ext3_new_blocks() [patch 5] Adjust reservation window size properly (by the given number of blocks to allocate) before block allocation to increase the possibility of allocating multiple blocks in a single call. Tests done so far includes fsx,tiobench and dbench. The following numbers collected from Direct IO tests (1G file creation/read) shows the system time have been greatly reduced (more than 50% on my 8 cpu system) with the patches. 1G file DIO write: 2.6.15 2.6.15+patches real 0m31.275s 0m31.161s user 0m0.000s 0m0.000s sys 0m3.384s 0m0.564s 1G file DIO read: 2.6.15 2.6.15+patches real 0m30.733s 0m30.624s user 0m0.000s 0m0.004s sys 0m0.748s 0m0.380s Some previous test we did on buffered IO with using multiple blocks allocation and delayed allocation shows noticeable improvement on throughput and system time. This patch: Add support of mapping multiple blocks in one call. This is useful for DIO reads and re-writes (where blocks are already allocated), also is in line with Christoph's proposal of using getblocks() in mpage_readpage() or mpage_readpages(). Signed-off-by: Mingming Cao <cmm@us.ibm.com> Cc: Badari Pulavarty <pbadari@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 01:37:55 -08:00
[PATCH] handle ext3 directory corruption better I've been using Steve Grubb's purely evil "fsfuzzer" tool, at http://people.redhat.com/sgrubb/files/fsfuzzer-0.4.tar.gz Basically it makes a filesystem, splats some random bits over it, then tries to mount it and do some simple filesystem actions. At best, the filesystem catches the corruption gracefully. At worst, things spin out of control. As you might guess, we found a couple places in ext3 where things spin out of control :) First, we had a corrupted directory that was never checked for consistency... it was corrupt, and pointed to another bad "entry" of length 0. The for() loop looped forever, since the length of ext3_next_entry(de) was 0, and we kept looking at the same pointer over and over and over and over... I modeled this check and subsequent action on what is done for other directory types in ext3_readdir... (adding this check adds some computational expense; I am testing a followup patch to reduce the number of times we check and re-check these directory entries, in all cases. Thanks for the idea, Andreas). Next we had a root directory inode which had a corrupted size, claimed to be > 200M on a 4M filesystem. There was only really 1 block in the directory, but because the size was so large, readdir kept coming back for more, spewing thousands of printk's along the way. Per Andreas' suggestion, if we're in this read error condition and we're trying to read an offset which is greater than i_blocks worth of bytes, stop trying, and break out of the loop. With these two changes fsfuzz test survives quite well on ext3. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-06 20:36:26 -08:00