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authorTrond Myklebust <trond.myklebust@primarydata.com>2015-02-05 17:27:39 -0500
committerTrond Myklebust <trond.myklebust@primarydata.com>2015-02-05 23:44:18 -0500
commit4ef2e4f84c523ebbc930ce05fa27b9b1350f4a4b (patch)
treea7c6f43fcf07eb6de7755152b38ae36d670910d5 /fs/nfs/pnfs.c
parente4af440aaf390ac1d39b26ef6cf4a28bcb6a5979 (diff)
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 <tao.peng@primarydata.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Diffstat (limited to 'fs/nfs/pnfs.c')
-rw-r--r--fs/nfs/pnfs.c53
1 files 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);