On Thu, Sep 6, 2012 at 3:51 PM, Josef Bacik <jba...@fusionio.com> wrote: > Mitch reported a problem where you could get an ENOSPC error when untarring > a kernel git tree onto a 16gb file system with compress-force=zlib. This is > because compression is a huge pain, it will return from ->writepages() > without having actually created any ordered extents. To get around this we > check to see if the async submit counter is up, and if it is wait until it > drops to 0 before doing our normal ordered wait dance. With this patch I > can now untar a kernel git tree onto a 16gb file system without getting > ENOSPC errors. Thanks, > > Signed-off-by: Josef Bacik <jba...@fusionio.com>
Thanks, this patch fixes the issues I was seeing with ENOSPC on zlib compression. I also did some rough testing for any performance regressions on lzo and with no compression, and my benchmarks were all in the same range. I don't have any comparisons available for zlib since my benchmark tests would always trigger ENOSPC errors. I also checked Zach Brown's suggestion of dropping: > + if (atomic_read(&root->fs_info->async_delalloc_pages)) and just leaving: > + wait_event(root->fs_info->async_submit_wait, > + !atomic_read(&root->fs_info->async_delalloc_pages)); This is because the wait_event macro should perform the same test (although it will start a 'do' loop before making the same test). This change also worked in my tests. For reference, I pulled up the wait_event macro according to the Linux Cross Reference site: http://lxr.free-electrons.com/source/include/linux/wait.h#L205 205 /** 206 * wait_event - sleep until a condition gets true 207 * @wq: the waitqueue to wait on 208 * @condition: a C expression for the event to wait for 209 * 210 * The process is put to sleep (TASK_UNINTERRUPTIBLE) until the 211 * @condition evaluates to true. The @condition is checked each time 212 * the waitqueue @wq is woken up. 213 * 214 * wake_up() has to be called after changing any variable that could 215 * change the result of the wait condition. 216 */ 217 #define wait_event(wq, condition) \ 218 do { \ 219 if (condition) \ 220 break; \ 221 __wait_event(wq, condition); \ 222 } while (0) Tested-by: Mitch Harder <mitch.har...@sabayonlinux.org> -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
