diff options
| -rw-r--r-- | module/zfs/zfs_vnops.c | 17 |
1 files changed, 15 insertions, 2 deletions
diff --git a/module/zfs/zfs_vnops.c b/module/zfs/zfs_vnops.c index a048aeb36..33cdbb3f5 100644 --- a/module/zfs/zfs_vnops.c +++ b/module/zfs/zfs_vnops.c @@ -3899,15 +3899,28 @@ zfs_putpage(struct inode *ip, struct page *pp, struct writeback_control *wbc) } #endif + /* + * The ordering here is critical and must adhere to the following + * rules in order to avoid deadlocking in either zfs_read() or + * zfs_free_range() due to a lock inversion. + * + * 1) The page must be unlocked prior to acquiring the range lock. + * This is critical because zfs_read() calls find_lock_page() + * which may block on the page lock while holding the range lock. + * + * 2) Before setting or clearing write back on a page the range lock + * must be held in order to prevent a lock inversion with the + * zfs_free_range() function. + */ + unlock_page(pp); rl = zfs_range_lock(zp, pgoff, pglen, RL_WRITER); - set_page_writeback(pp); - unlock_page(pp); tx = dmu_tx_create(zsb->z_os); dmu_tx_hold_write(tx, zp->z_id, pgoff, pglen); dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_FALSE); zfs_sa_upgrade_txholds(tx, zp); + err = dmu_tx_assign(tx, TXG_NOWAIT); if (err != 0) { if (err == ERESTART) |