Messages in this thread Patch in this message | | | Subject | Re: [vm] writing to UDF DVD+RW (/dev/sr0) while under memory pressure: box ==> doorstop | From | Mike Galbraith <> | Date | Thu, 10 Jan 2008 16:29:50 +0100 |
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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 <efault@gmx.de>
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;
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