Fix regression in dmu_buf_will_fill()

Direct I/O implementation added condition to call dbuf_undirty()
only in case of block cloning.  But the condition is not right if
the block is no longer dirty in this TXG, but still in DB_NOFILL
state.  It resulted in block not reverting to DB_UNCACHED and
following NULL de-reference on attempt to access absent db_data.

While there, add assertions for db_data to make debugging easier.

Reviewed-by: Brian Atkinson <batkinson@lanl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alexander Motin <mav@FreeBSD.org>
Sponsored by:	iXsystems, Inc.
Closes #16829
This commit is contained in:
Alexander Motin 2024-12-02 20:08:40 -05:00 committed by Brian Behlendorf
parent 17cdb7a2b1
commit b17ea73f9d
3 changed files with 11 additions and 2 deletions

View File

@ -103,6 +103,7 @@ dmu_write_pages(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
db->db_offset + bufoff);
thiscpy = MIN(PAGESIZE, tocpy - copied);
va = zfs_map_page(*ma, &sf);
ASSERT(db->db_data != NULL);
memcpy((char *)db->db_data + bufoff, va, thiscpy);
zfs_unmap_page(sf);
ma += 1;
@ -172,6 +173,7 @@ dmu_read_pages(objset_t *os, uint64_t object, vm_page_t *ma, int count,
ASSERT3U(db->db_size, >, PAGE_SIZE);
bufoff = IDX_TO_OFF(m->pindex) % db->db_size;
va = zfs_map_page(m, &sf);
ASSERT(db->db_data != NULL);
memcpy(va, (char *)db->db_data + bufoff, PAGESIZE);
zfs_unmap_page(sf);
vm_page_valid(m);
@ -211,8 +213,10 @@ dmu_read_pages(objset_t *os, uint64_t object, vm_page_t *ma, int count,
*/
tocpy = MIN(db->db_size - bufoff, PAGESIZE - pgoff);
ASSERT3S(tocpy, >=, 0);
if (m != bogus_page)
if (m != bogus_page) {
ASSERT(db->db_data != NULL);
memcpy(va + pgoff, (char *)db->db_data + bufoff, tocpy);
}
pgoff += tocpy;
ASSERT3S(pgoff, >=, 0);
@ -290,6 +294,7 @@ dmu_read_pages(objset_t *os, uint64_t object, vm_page_t *ma, int count,
bufoff = IDX_TO_OFF(m->pindex) % db->db_size;
tocpy = MIN(db->db_size - bufoff, PAGESIZE);
va = zfs_map_page(m, &sf);
ASSERT(db->db_data != NULL);
memcpy(va, (char *)db->db_data + bufoff, tocpy);
if (tocpy < PAGESIZE) {
ASSERT3S(i, ==, *rahead - 1);

View File

@ -2921,7 +2921,7 @@ dmu_buf_will_fill(dmu_buf_t *db_fake, dmu_tx_t *tx, boolean_t canfail)
* pending clone and mark the block as uncached. This will be
* as if the clone was never done.
*/
if (dr && dr->dt.dl.dr_brtwrite) {
if (db->db_state == DB_NOFILL) {
VERIFY(!dbuf_undirty(db, tx));
db->db_state = DB_UNCACHED;
}

View File

@ -1221,6 +1221,7 @@ dmu_read_impl(dnode_t *dn, uint64_t offset, uint64_t size,
bufoff = offset - db->db_offset;
tocpy = MIN(db->db_size - bufoff, size);
ASSERT(db->db_data != NULL);
(void) memcpy(buf, (char *)db->db_data + bufoff, tocpy);
offset += tocpy;
@ -1278,6 +1279,7 @@ dmu_write_impl(dmu_buf_t **dbp, int numbufs, uint64_t offset, uint64_t size,
else
dmu_buf_will_dirty(db, tx);
ASSERT(db->db_data != NULL);
(void) memcpy((char *)db->db_data + bufoff, buf, tocpy);
if (tocpy == db->db_size)
@ -1426,6 +1428,7 @@ dmu_read_uio_dnode(dnode_t *dn, zfs_uio_t *uio, uint64_t size)
bufoff = zfs_uio_offset(uio) - db->db_offset;
tocpy = MIN(db->db_size - bufoff, size);
ASSERT(db->db_data != NULL);
err = zfs_uio_fault_move((char *)db->db_data + bufoff, tocpy,
UIO_READ, uio);
@ -1550,6 +1553,7 @@ top:
else
dmu_buf_will_dirty(db, tx);
ASSERT(db->db_data != NULL);
err = zfs_uio_fault_move((char *)db->db_data + bufoff,
tocpy, UIO_WRITE, uio);