From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [vm] writing to UDF DVD+RW (/dev/sr0) while under memory pressure: box ==> doorstop From: Mike Galbraith In-Reply-To: <20080110144123.GA12331@atrey.karlin.mff.cuni.cz> References: <1199447212.4529.13.camel@homer.simson.net> <1199612533.4384.54.camel@homer.simson.net> <1199642470.3927.12.camel@homer.simson.net> <20080106122954.d8f04c98.akpm@linux-foundation.org> <1199790316.4094.57.camel@homer.simson.net> <20080108033801.40d0043a.akpm@linux-foundation.org> <1199805713.3571.12.camel@homer.simson.net> <1199806071.4174.2.camel@homer.simson.net> <1199877080.4340.19.camel@homer.simson.net> <20080109150139.311f68d3.akpm@linux-foundation.org> <20080110144123.GA12331@atrey.karlin.mff.cuni.cz> Content-Type: text/plain Date: Thu, 10 Jan 2008 16:29:50 +0100 Message-Id: <1199978990.4196.53.camel@homer.simson.net> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Jan Kara Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, bfennema@falcon.csc.calpoly.edu List-ID: On Thu, 2008-01-10 at 15:41 +0100, Jan Kara wrote: > > On Wed, 09 Jan 2008 12:11:20 +0100 > > > > > > I wonder why UDF was doing a synchronous write in there. In fact I wonder > > why it's writing the inode at all? extN doesn't do that. If for some > > reason it really does want to make the inode immediately reclaimable then > > simply shoving it down into the /dev/hda1 pagecache should be sufficient > > (ie: what you did).. > Looking at the code, I think UDF change is correct. UDF has to call > write_inode_now() because by the time clear_inode() is called, inode is > already written by VFS and prepared to be freed. But then UDF modifies > it in udf_clear_inode() (removes preallocation) and for these changes to > get to disk you have to write the inode explicitely. > But there's really no need to wait on IO. We only have to copy all > data from inode structure into buffers and that happens even if we don't > wait on sync. Perhaps I should go ahead and submit it then. There are 5 other async callers as well, so VM/UDF reclaim buglet can die, and those others can get what they asked for with net diffstat of 0. Fix udf_clear_inode() to request asynchronous writeout in icache reclaim path, and ensure that write_inore_now() honors that request, lest allocators needlessly block on iprune_mutex. Signed-off-by: Mike Galbraith diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 0fca820..f1cce24 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -657,7 +657,7 @@ int write_inode_now(struct inode *inode, int sync) int ret; struct writeback_control wbc = { .nr_to_write = LONG_MAX, - .sync_mode = WB_SYNC_ALL, + .sync_mode = sync ? WB_SYNC_ALL : WB_SYNC_NONE, .range_start = 0, .range_end = LLONG_MAX, }; diff --git a/fs/udf/inode.c b/fs/udf/inode.c index 6ff8151..d1fc116 100644 --- a/fs/udf/inode.c +++ b/fs/udf/inode.c @@ -117,7 +117,7 @@ void udf_clear_inode(struct inode *inode) udf_discard_prealloc(inode); udf_truncate_tail_extent(inode); unlock_kernel(); - write_inode_now(inode, 1); + write_inode_now(inode, 0); } kfree(UDF_I_DATA(inode)); UDF_I_DATA(inode) = NULL; -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org