On Thu, Sep 24, 2020 at 11:39:11AM -0500, Goldwyn Rodrigues wrote: > From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx> > > iomap complete routine can deadlock with btrfs_fallocate because of the > call to generic_write_sync(). > > P0 P1 > inode_lock() fallocate(FALLOC_FL_ZERO_RANGE) > __iomap_dio_rw() inode_lock() > <block> > <submits IO> > <completes IO> > inode_unlock() > <gets inode_lock()> > inode_dio_wait() > iomap_dio_complete() > generic_write_sync() > btrfs_file_fsync() > inode_lock() > <deadlock> > > inode_dio_end() is used to notify the end of DIO data in order > to synchronize with truncate. Call inode_dio_end() before calling > generic_write_sync(), so filesystems can lock i_rwsem during a sync. > > This matches the way it is done in fs/direct-io.c:dio_complete(). > > Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx> > Reviewed-by: Christoph Hellwig <hch@xxxxxx> > Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx> Looks ok (at least with the fses that use either iomap or ye olde directio) to me... Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> So, uh, do you want me to pull these two iomap patches in for 5.10? --D > --- > fs/iomap/direct-io.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c > index b88dbfe15118..0ea88ae57cb2 100644 > --- a/fs/iomap/direct-io.c > +++ b/fs/iomap/direct-io.c > @@ -118,6 +118,7 @@ ssize_t iomap_dio_complete(struct iomap_dio *dio) > dio_warn_stale_pagecache(iocb->ki_filp); > } > > + inode_dio_end(file_inode(iocb->ki_filp)); > /* > * If this is a DSYNC write, make sure we push it to stable storage now > * that we've written data. > @@ -125,7 +126,6 @@ ssize_t iomap_dio_complete(struct iomap_dio *dio) > if (ret > 0 && (dio->flags & IOMAP_DIO_NEED_SYNC)) > ret = generic_write_sync(iocb, ret); > > - inode_dio_end(file_inode(iocb->ki_filp)); > kfree(dio); > > return ret; > -- > 2.26.2 >
