From 4ef2e4f84c523ebbc930ce05fa27b9b1350f4a4b Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Thu, 5 Feb 2015 17:27:39 -0500 Subject: [PATCH] NFSv4.1: Fix pnfs_put_lseg races pnfs_layoutreturn_free_lseg_async() can also race with inode put in the general case. We can now fix this, and also simplify the code. Cc: Peng Tao Signed-off-by: Trond Myklebust --- fs/nfs/pnfs.c | 53 ++++++++++++++++++--------------------------------- 1 file changed, 19 insertions(+), 34 deletions(-) diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c index a1d8620e8cb7..107b321be7d4 100644 --- a/fs/nfs/pnfs.c +++ b/fs/nfs/pnfs.c @@ -361,14 +361,9 @@ pnfs_layout_need_return(struct pnfs_layout_hdr *lo, return true; } -static void pnfs_layoutreturn_free_lseg(struct work_struct *work) +static void pnfs_layoutreturn_before_put_lseg(struct pnfs_layout_segment *lseg, + struct pnfs_layout_hdr *lo, struct inode *inode) { - struct pnfs_layout_segment *lseg; - struct pnfs_layout_hdr *lo; - struct inode *inode; - - lseg = container_of(work, struct pnfs_layout_segment, pls_work); - WARN_ON(atomic_read(&lseg->pls_refcount)); lo = lseg->pls_layout; inode = lo->plh_inode; @@ -383,24 +378,12 @@ static void pnfs_layoutreturn_free_lseg(struct work_struct *work) lo->plh_block_lgets++; lo->plh_return_iomode = 0; spin_unlock(&inode->i_lock); + pnfs_get_layout_hdr(lo); - pnfs_send_layoutreturn(lo, stateid, iomode, true); - spin_lock(&inode->i_lock); + /* Send an async layoutreturn so we dont deadlock */ + pnfs_send_layoutreturn(lo, stateid, iomode, false); } else - /* match pnfs_get_layout_hdr #2 in pnfs_put_lseg */ - pnfs_put_layout_hdr(lo); - pnfs_layout_remove_lseg(lo, lseg); - spin_unlock(&inode->i_lock); - pnfs_free_lseg(lseg); - /* match pnfs_get_layout_hdr #1 in pnfs_put_lseg */ - pnfs_put_layout_hdr(lo); -} - -static void -pnfs_layoutreturn_free_lseg_async(struct pnfs_layout_segment *lseg) -{ - INIT_WORK(&lseg->pls_work, pnfs_layoutreturn_free_lseg); - queue_work(nfsiod_workqueue, &lseg->pls_work); + spin_unlock(&inode->i_lock); } void @@ -415,21 +398,23 @@ pnfs_put_lseg(struct pnfs_layout_segment *lseg) dprintk("%s: lseg %p ref %d valid %d\n", __func__, lseg, atomic_read(&lseg->pls_refcount), test_bit(NFS_LSEG_VALID, &lseg->pls_flags)); + + /* Handle the case where refcount != 1 */ + if (atomic_add_unless(&lseg->pls_refcount, -1, 1)) + return; + lo = lseg->pls_layout; inode = lo->plh_inode; + /* Do we need a layoutreturn? */ + if (test_bit(NFS_LSEG_LAYOUTRETURN, &lseg->pls_flags)) + pnfs_layoutreturn_before_put_lseg(lseg, lo, inode); + if (atomic_dec_and_lock(&lseg->pls_refcount, &inode->i_lock)) { pnfs_get_layout_hdr(lo); - if (pnfs_layout_need_return(lo, lseg)) { - spin_unlock(&inode->i_lock); - /* hdr reference dropped in nfs4_layoutreturn_release */ - pnfs_get_layout_hdr(lo); - pnfs_layoutreturn_free_lseg_async(lseg); - } else { - pnfs_layout_remove_lseg(lo, lseg); - spin_unlock(&inode->i_lock); - pnfs_free_lseg(lseg); - pnfs_put_layout_hdr(lo); - } + pnfs_layout_remove_lseg(lo, lseg); + spin_unlock(&inode->i_lock); + pnfs_free_lseg(lseg); + pnfs_put_layout_hdr(lo); } } EXPORT_SYMBOL_GPL(pnfs_put_lseg); -- 2.20.1