Hey Christoph, On Tue, Dec 20, 2011 at 03:08:41PM -0500, Christoph Hellwig wrote: > Since Linux 2.6.36 the writeback code has introduces various measures for > live lock prevention during sync(). Unfortunately some of these are > actively harmful for the XFS model, where the inode gets marked dirty for > metadata from the data I/O handler. > > The older_than_this checks that are now more strictly enforced since > > writeback: avoid livelocking WB_SYNC_ALL writeback > > by only calling into __writeback_inodes_sb and thus only sampling the Do you mean __writeback_inodes_wb, or perhaps writeback_sb_inodes? So far I'm not seeing the connection with the commit you've referenced above, which seems to be related to nr_to_write. It looks like you're referring to older fs/fs-writeback.c.. This one seems like it might be relevant: commit 7624ee7 mm: avoid resetting wb_start after each writeback round Anyway.. in the 3.2-rcX code it appears that older_than_this is only set at the start of wb_writeback (excluding for_kupdate being set)... > current cut off time once. But on a slow enough devices the previous > asynchronous sync pass might not have fully completed yet, and thus XFS > might mark metadata dirty only after that sampling of the cut off time for > the blocking pass already happened. Are you referring to sync_filesystem() calling __sync_filesystem(sb, 0) and then __sync_filesystem(sb, 1 /* wait */)? Ah... and with that I think I understand what you're after here: After __sync_filesystem calls sync_inodes_sb and waits for completion... which will dirty more inodes in completion handlers... you have the opportunity to clean up those dirty inodes in .sync_fs. If that's what you intend: I'd say this looks good. Reviewed-by: Ben Myers <bpm@xxxxxxx> Mark also reviewed this. Reviewed-by: Mark Tinguely <tinguely@xxxxxxx> THanks, Ben _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
