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Fix zfs_get_data access to files with wrong generation
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If TX_WRITE is create on a file, and the file is later deleted and a new
directory is created on the same object id, it is possible that when
zil_commit happens, zfs_get_data will be called on the new directory.
This may result in panic as it tries to do range lock.

This patch fixes this issue by record the generation number during
zfs_log_write, so zfs_get_data can check if the object is valid.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Chunwei Chen <[email protected]>
Closes openzfs#10593
Closes openzfs#11682
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tuxoko authored and RageLtMan committed May 31, 2021
1 parent c9ae64e commit e096193
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Showing 6 changed files with 26 additions and 6 deletions.
4 changes: 2 additions & 2 deletions cmd/ztest/ztest.c
Original file line number Diff line number Diff line change
Expand Up @@ -2291,8 +2291,8 @@ ztest_get_done(zgd_t *zgd, int error)
}

static int
ztest_get_data(void *arg, lr_write_t *lr, char *buf, struct lwb *lwb,
zio_t *zio)
ztest_get_data(void *arg, uint64_t arg2, lr_write_t *lr, char *buf,
struct lwb *lwb, zio_t *zio)
{
ztest_ds_t *zd = arg;
objset_t *os = zd->zd_os;
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3 changes: 2 additions & 1 deletion include/sys/zil.h
Original file line number Diff line number Diff line change
Expand Up @@ -399,6 +399,7 @@ typedef struct itx {
void *itx_callback_data; /* User data for the callback */
size_t itx_size; /* allocated itx structure size */
uint64_t itx_oid; /* object id */
uint64_t itx_gen; /* gen number for zfs_get_data */
lr_t itx_lr; /* common part of log record */
/* followed by type-specific part of lr_xx_t and its immediate data */
} itx_t;
Expand Down Expand Up @@ -467,7 +468,7 @@ typedef int zil_parse_blk_func_t(zilog_t *zilog, const blkptr_t *bp, void *arg,
typedef int zil_parse_lr_func_t(zilog_t *zilog, const lr_t *lr, void *arg,
uint64_t txg);
typedef int zil_replay_func_t(void *arg1, void *arg2, boolean_t byteswap);
typedef int zil_get_data_t(void *arg, lr_write_t *lr, char *dbuf,
typedef int zil_get_data_t(void *arg, uint64_t arg2, lr_write_t *lr, char *dbuf,
struct lwb *lwb, zio_t *zio);

extern int zil_parse(zilog_t *zilog, zil_parse_blk_func_t *parse_blk_func,
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5 changes: 5 additions & 0 deletions module/zfs/zfs_log.c
Original file line number Diff line number Diff line change
Expand Up @@ -540,6 +540,7 @@ zfs_log_write(zilog_t *zilog, dmu_tx_t *tx, int txtype,
uint32_t blocksize = zp->z_blksz;
itx_wr_state_t write_state;
uintptr_t fsync_cnt;
uint64_t gen = 0;

if (zil_replaying(zilog, tx) || zp->z_unlinked ||
zfs_xattr_owner_unlinked(zp)) {
Expand All @@ -562,6 +563,9 @@ zfs_log_write(zilog_t *zilog, dmu_tx_t *tx, int txtype,
(void) tsd_set(zfs_fsyncer_key, (void *)(fsync_cnt - 1));
}

(void) sa_lookup(zp->z_sa_hdl, SA_ZPL_GEN(ZTOZSB(zp)), &gen,
sizeof (gen));

while (resid) {
itx_t *itx;
lr_write_t *lr;
Expand Down Expand Up @@ -609,6 +613,7 @@ zfs_log_write(zilog_t *zilog, dmu_tx_t *tx, int txtype,
BP_ZERO(&lr->lr_blkptr);

itx->itx_private = ZTOZSB(zp);
itx->itx_gen = gen;

if (!(ioflag & (O_SYNC | O_DSYNC)) && (zp->z_sync_cnt == 0) &&
(fsync_cnt == 0))
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14 changes: 13 additions & 1 deletion module/zfs/zfs_vnops.c
Original file line number Diff line number Diff line change
Expand Up @@ -1395,7 +1395,8 @@ static void zfs_get_done(zgd_t *zgd, int error);
* Get data to generate a TX_WRITE intent log record.
*/
int
zfs_get_data(void *arg, lr_write_t *lr, char *buf, struct lwb *lwb, zio_t *zio)
zfs_get_data(void *arg, uint64_t gen, lr_write_t *lr, char *buf,
struct lwb *lwb, zio_t *zio)
{
zfsvfs_t *zfsvfs = arg;
objset_t *os = zfsvfs->z_os;
Expand All @@ -1406,6 +1407,7 @@ zfs_get_data(void *arg, lr_write_t *lr, char *buf, struct lwb *lwb, zio_t *zio)
dmu_buf_t *db;
zgd_t *zgd;
int error = 0;
uint64_t zp_gen;

ASSERT3P(lwb, !=, NULL);
ASSERT3P(zio, !=, NULL);
Expand All @@ -1424,6 +1426,16 @@ zfs_get_data(void *arg, lr_write_t *lr, char *buf, struct lwb *lwb, zio_t *zio)
zfs_zrele_async(zp);
return (SET_ERROR(ENOENT));
}
/* check if generation number matches */
if (sa_lookup(zp->z_sa_hdl, SA_ZPL_GEN(zfsvfs), &zp_gen,
sizeof (zp_gen)) != 0) {
zfs_zrele_async(zp);
return (SET_ERROR(EIO));
}
if (zp_gen != gen) {
zfs_zrele_async(zp);
return (SET_ERROR(ENOENT));
}

zgd = (zgd_t *)kmem_zalloc(sizeof (zgd_t), KM_SLEEP);
zgd->zgd_lwb = lwb;
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3 changes: 2 additions & 1 deletion module/zfs/zil.c
Original file line number Diff line number Diff line change
Expand Up @@ -1744,7 +1744,8 @@ zil_lwb_commit(zilog_t *zilog, itx_t *itx, lwb_t *lwb)
* completed after "lwb_write_zio" completed.
*/
error = zilog->zl_get_data(itx->itx_private,
lrwb, dbuf, lwb, lwb->lwb_write_zio);
itx->itx_gen, lrwb, dbuf, lwb,
lwb->lwb_write_zio);

if (error == EIO) {
txg_wait_synced(zilog->zl_dmu_pool, txg);
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3 changes: 2 additions & 1 deletion module/zfs/zvol.c
Original file line number Diff line number Diff line change
Expand Up @@ -672,7 +672,8 @@ zvol_get_done(zgd_t *zgd, int error)
* Get data to generate a TX_WRITE intent log record.
*/
int
zvol_get_data(void *arg, lr_write_t *lr, char *buf, struct lwb *lwb, zio_t *zio)
zvol_get_data(void *arg, lr_write_t *lr, char *buf, struct lwb *lwb,
zio_t *zio)
{
zvol_state_t *zv = arg;
uint64_t offset = lr->lr_offset;
Expand Down

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