Fix corruption caused by mmap flushing problems

1) Make mmap flushes synchronous. Linux may skip flushing dirty pages
   already in writeback unless data-integrity sync is requested.

2) Change zfs_putpage to use TXG_WAIT. Otherwise dirty pages may be
   skipped due to DMU pushing back on TX assign.

3) Add missing mmap flush when doing block cloning.

4) While here, pass errors from putpage to writepage/writepages.

This change fixes corruption edge cases, but unfortunately adds
synchronous ZIL flushes for dirty mmap pages to llseek and bclone
operations. It may be possible to avoid these sync writes later
but would need more tricky refactoring of the writeback code.

Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Robert Evans <evansr@google.com>
Closes #15933
Closes #16019

diff --git a/module/os/linux/zfs/zfs_vnops_os.c b/module/os/linux/zfs/zfs_vnops_os.c
index a32307c393314d4dc9ed6d2c608ae68b62de6d2b..1cecad9f77559164d68bfb7d0a59c35c34e2252b 100644 (file)
--- a/module/os/linux/zfs/zfs_vnops_os.c
+++ b/module/os/linux/zfs/zfs_vnops_os.c
@@ -3795,11 +3795,8 @@ zfs_putpage(struct inode *ip, struct page *pp, struct writeback_control *wbc,
        dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_FALSE);
        zfs_sa_upgrade_txholds(tx, zp);
 
-       err = dmu_tx_assign(tx, TXG_NOWAIT);
+       err = dmu_tx_assign(tx, TXG_WAIT);
        if (err != 0) {
-               if (err == ERESTART)
-                       dmu_tx_wait(tx);
-
                dmu_tx_abort(tx);
 #ifdef HAVE_VFS_FILEMAP_DIRTY_FOLIO
                filemap_dirty_folio(page_mapping(pp), page_folio(pp));

diff --git a/module/os/linux/zfs/zpl_file.c b/module/os/linux/zfs/zpl_file.c
index 3caa0fc6c214f581c9ebddb5648e99e0490b1365..9dec52215c7c4409b21659ba242f1c20760de828 100644 (file)
--- a/module/os/linux/zfs/zpl_file.c
+++ b/module/os/linux/zfs/zpl_file.c
@@ -720,23 +720,23 @@ zpl_putpage(struct page *pp, struct writeback_control *wbc, void *data)
 {
        boolean_t *for_sync = data;
        fstrans_cookie_t cookie;
+       int ret;
 
        ASSERT(PageLocked(pp));
        ASSERT(!PageWriteback(pp));
 
        cookie = spl_fstrans_mark();
-       (void) zfs_putpage(pp->mapping->host, pp, wbc, *for_sync);
+       ret = zfs_putpage(pp->mapping->host, pp, wbc, *for_sync);
        spl_fstrans_unmark(cookie);
 
-       return (0);
+       return (ret);
 }
 
 #ifdef HAVE_WRITEPAGE_T_FOLIO
 static int
 zpl_putfolio(struct folio *pp, struct writeback_control *wbc, void *data)
 {
-       (void) zpl_putpage(&pp->page, wbc, data);
-       return (0);
+       return (zpl_putpage(&pp->page, wbc, data));
 }
 #endif
 

diff --git a/module/zfs/zfs_vnops.c b/module/zfs/zfs_vnops.c
index 7f39ad6fc775e5d8a8b6fc24f105b600b87dafc8..babb07ca25a99259aee9950c0c01c74b62ecfcbb 100644 (file)
--- a/module/zfs/zfs_vnops.c
+++ b/module/zfs/zfs_vnops.c
@@ -123,7 +123,7 @@ zfs_holey_common(znode_t *zp, ulong_t cmd, loff_t *off)
 
        /* Flush any mmap()'d data to disk */
        if (zn_has_cached_data(zp, 0, file_sz - 1))
-               zn_flush_cached_data(zp, B_FALSE);
+               zn_flush_cached_data(zp, B_TRUE);
 
        lr = zfs_rangelock_enter(&zp->z_rangelock, 0, UINT64_MAX, RL_READER);
        error = dmu_offset_next(ZTOZSB(zp)->z_os, zp->z_id, hole, &noff);
@@ -1187,6 +1187,10 @@ zfs_clone_range(znode_t *inzp, uint64_t *inoffp, znode_t *outzp,
                }
        }
 
+       /* Flush any mmap()'d data to disk */
+       if (zn_has_cached_data(inzp, inoff, inoff + len - 1))
+               zn_flush_cached_data(inzp, B_TRUE);
+
        /*
         * Maintain predictable lock order.
         */