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-rw-r--r--module/zfs/arc.c19
-rw-r--r--module/zfs/dbuf.c24
-rw-r--r--module/zfs/dmu.c2
-rw-r--r--module/zfs/dmu_tx.c8
-rw-r--r--module/zfs/dmu_zfetch.c12
-rw-r--r--module/zfs/spa.c2
-rw-r--r--module/zfs/txg.c14
-rw-r--r--module/zfs/vdev_label.c1
-rw-r--r--module/zfs/vdev_raidz.c65
-rw-r--r--module/zfs/zfs_ctldir.c5
10 files changed, 141 insertions, 11 deletions
diff --git a/module/zfs/arc.c b/module/zfs/arc.c
index a521501bd..2ae4c37a3 100644
--- a/module/zfs/arc.c
+++ b/module/zfs/arc.c
@@ -260,7 +260,18 @@ typedef struct arc_stats {
kstat_named_t arcstat_mfu_ghost_hits;
kstat_named_t arcstat_deleted;
kstat_named_t arcstat_recycle_miss;
+ /*
+ * Number of buffers that could not be evicted because the hash lock
+ * was held by another thread. The lock may not necessarily be held
+ * by something using the same buffer, since hash locks are shared
+ * by multiple buffers.
+ */
kstat_named_t arcstat_mutex_miss;
+ /*
+ * Number of buffers skipped because they have I/O in progress, are
+ * indrect prefetch buffers that have not lived long enough, or are
+ * not from the spa we're trying to evict from.
+ */
kstat_named_t arcstat_evict_skip;
kstat_named_t arcstat_evict_l2_cached;
kstat_named_t arcstat_evict_l2_eligible;
@@ -3174,6 +3185,10 @@ top:
mutex_exit(hash_lock);
+ /*
+ * At this point, we have a level 1 cache miss. Try again in
+ * L2ARC if possible.
+ */
ASSERT3U(hdr->b_size, ==, size);
DTRACE_PROBE4(arc__miss, arc_buf_hdr_t *, hdr, blkptr_t *, bp,
uint64_t, size, zbookmark_t *, zb);
@@ -3445,8 +3460,8 @@ arc_buf_evict(arc_buf_t *buf)
}
/*
- * Release this buffer from the cache. This must be done
- * after a read and prior to modifying the buffer contents.
+ * Release this buffer from the cache, making it an anonymous buffer. This
+ * must be done after a read and prior to modifying the buffer contents.
* If the buffer has more than one reference, we must make
* a new hdr for the buffer.
*/
diff --git a/module/zfs/dbuf.c b/module/zfs/dbuf.c
index 9c60ec55a..95c7b3297 100644
--- a/module/zfs/dbuf.c
+++ b/module/zfs/dbuf.c
@@ -691,6 +691,14 @@ dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags)
if (!havepzio)
err = zio_wait(zio);
} else {
+ /*
+ * Another reader came in while the dbuf was in flight
+ * between UNCACHED and CACHED. Either a writer will finish
+ * writing the buffer (sending the dbuf to CACHED) or the
+ * first reader's request will reach the read_done callback
+ * and send the dbuf to CACHED. Otherwise, a failure
+ * occurred and the dbuf went to UNCACHED.
+ */
mutex_exit(&db->db_mtx);
if (prefetch)
dmu_zfetch(&dn->dn_zfetch, db->db.db_offset,
@@ -699,6 +707,7 @@ dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags)
rw_exit(&dn->dn_struct_rwlock);
DB_DNODE_EXIT(db);
+ /* Skip the wait per the caller's request. */
mutex_enter(&db->db_mtx);
if ((flags & DB_RF_NEVERWAIT) == 0) {
while (db->db_state == DB_READ ||
@@ -1313,7 +1322,8 @@ dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
}
/*
- * Return TRUE if this evicted the dbuf.
+ * Undirty a buffer in the transaction group referenced by the given
+ * transaction. Return whether this evicted the dbuf.
*/
static boolean_t
dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
@@ -2324,6 +2334,7 @@ dbuf_sync_indirect(dbuf_dirty_record_t *dr, dmu_tx_t *tx)
ASSERT(db->db_level > 0);
DBUF_VERIFY(db);
+ /* Read the block if it hasn't been read yet. */
if (db->db_buf == NULL) {
mutex_exit(&db->db_mtx);
(void) dbuf_read(db, NULL, DB_RF_MUST_SUCCEED);
@@ -2334,10 +2345,12 @@ dbuf_sync_indirect(dbuf_dirty_record_t *dr, dmu_tx_t *tx)
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
+ /* Indirect block size must match what the dnode thinks it is. */
ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
dbuf_check_blkptr(dn, db);
DB_DNODE_EXIT(db);
+ /* Provide the pending dirty record to child dbufs */
db->db_data_pending = dr;
mutex_exit(&db->db_mtx);
@@ -2728,6 +2741,7 @@ dbuf_write_override_done(zio_t *zio)
dbuf_write_done(zio, NULL, db);
}
+/* Issue I/O to commit a dirty buffer to disk. */
static void
dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx)
{
@@ -2762,11 +2776,19 @@ dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx)
}
if (parent != dn->dn_dbuf) {
+ /* Our parent is an indirect block. */
+ /* We have a dirty parent that has been scheduled for write. */
ASSERT(parent && parent->db_data_pending);
+ /* Our parent's buffer is one level closer to the dnode. */
ASSERT(db->db_level == parent->db_level-1);
+ /*
+ * We're about to modify our parent's db_data by modifying
+ * our block pointer, so the parent must be released.
+ */
ASSERT(arc_released(parent->db_buf));
zio = parent->db_data_pending->dr_zio;
} else {
+ /* Our parent is the dnode itself. */
ASSERT((db->db_level == dn->dn_phys->dn_nlevels-1 &&
db->db_blkid != DMU_SPILL_BLKID) ||
(db->db_blkid == DMU_SPILL_BLKID && db->db_level == 0));
diff --git a/module/zfs/dmu.c b/module/zfs/dmu.c
index 9223b907b..34f3eeef9 100644
--- a/module/zfs/dmu.c
+++ b/module/zfs/dmu.c
@@ -1965,7 +1965,7 @@ dmu_init(void)
void
dmu_fini(void)
{
- arc_fini();
+ arc_fini(); /* arc depends on l2arc, so arc must go first */
l2arc_fini();
dmu_tx_fini();
zfetch_fini();
diff --git a/module/zfs/dmu_tx.c b/module/zfs/dmu_tx.c
index 1cad8d20e..caac60193 100644
--- a/module/zfs/dmu_tx.c
+++ b/module/zfs/dmu_tx.c
@@ -1040,6 +1040,10 @@ dmu_tx_unassign(dmu_tx_t *tx)
txg_rele_to_quiesce(&tx->tx_txgh);
+ /*
+ * Walk the transaction's hold list, removing the hold on the
+ * associated dnode, and notifying waiters if the refcount drops to 0.
+ */
for (txh = list_head(&tx->tx_holds); txh != tx->tx_needassign_txh;
txh = list_next(&tx->tx_holds, txh)) {
dnode_t *dn = txh->txh_dnode;
@@ -1157,6 +1161,10 @@ dmu_tx_commit(dmu_tx_t *tx)
ASSERT(tx->tx_txg != 0);
+ /*
+ * Go through the transaction's hold list and remove holds on
+ * associated dnodes, notifying waiters if no holds remain.
+ */
while ((txh = list_head(&tx->tx_holds))) {
dnode_t *dn = txh->txh_dnode;
diff --git a/module/zfs/dmu_zfetch.c b/module/zfs/dmu_zfetch.c
index 1763bae51..705478c82 100644
--- a/module/zfs/dmu_zfetch.c
+++ b/module/zfs/dmu_zfetch.c
@@ -48,11 +48,11 @@ unsigned int zfetch_block_cap = 256;
unsigned long zfetch_array_rd_sz = 1024 * 1024;
/* forward decls for static routines */
-static int dmu_zfetch_colinear(zfetch_t *, zstream_t *);
+static boolean_t dmu_zfetch_colinear(zfetch_t *, zstream_t *);
static void dmu_zfetch_dofetch(zfetch_t *, zstream_t *);
static uint64_t dmu_zfetch_fetch(dnode_t *, uint64_t, uint64_t);
static uint64_t dmu_zfetch_fetchsz(dnode_t *, uint64_t, uint64_t);
-static int dmu_zfetch_find(zfetch_t *, zstream_t *, int);
+static boolean_t dmu_zfetch_find(zfetch_t *, zstream_t *, int);
static int dmu_zfetch_stream_insert(zfetch_t *, zstream_t *);
static zstream_t *dmu_zfetch_stream_reclaim(zfetch_t *);
static void dmu_zfetch_stream_remove(zfetch_t *, zstream_t *);
@@ -104,9 +104,9 @@ kstat_t *zfetch_ksp;
* last stream, then we are probably in a strided access pattern. So
* combine the two sequential streams into a single strided stream.
*
- * If no co-linear streams are found, return NULL.
+ * Returns whether co-linear streams were found.
*/
-static int
+static boolean_t
dmu_zfetch_colinear(zfetch_t *zf, zstream_t *zh)
{
zstream_t *z_walk;
@@ -326,7 +326,7 @@ dmu_zfetch_fetchsz(dnode_t *dn, uint64_t blkid, uint64_t nblks)
* for this block read. If so, it starts a prefetch for the stream it
* located and returns true, otherwise it returns false
*/
-static int
+static boolean_t
dmu_zfetch_find(zfetch_t *zf, zstream_t *zh, int prefetched)
{
zstream_t *zs;
@@ -639,7 +639,7 @@ dmu_zfetch(zfetch_t *zf, uint64_t offset, uint64_t size, int prefetched)
{
zstream_t zst;
zstream_t *newstream;
- int fetched;
+ boolean_t fetched;
int inserted;
unsigned int blkshft;
uint64_t blksz;
diff --git a/module/zfs/spa.c b/module/zfs/spa.c
index bc9bf2cc3..c30107771 100644
--- a/module/zfs/spa.c
+++ b/module/zfs/spa.c
@@ -26,6 +26,8 @@
*/
/*
+ * SPA: Storage Pool Allocator
+ *
* This file contains all the routines used when modifying on-disk SPA state.
* This includes opening, importing, destroying, exporting a pool, and syncing a
* pool.
diff --git a/module/zfs/txg.c b/module/zfs/txg.c
index c8a29e14f..697aa0905 100644
--- a/module/zfs/txg.c
+++ b/module/zfs/txg.c
@@ -354,6 +354,12 @@ txg_rele_to_sync(txg_handle_t *th)
th->th_cpu = NULL; /* defensive */
}
+/*
+ * Blocks until all transactions in the group are committed.
+ *
+ * On return, the transaction group has reached a stable state in which it can
+ * then be passed off to the syncing context.
+ */
static void
txg_quiesce(dsl_pool_t *dp, uint64_t txg)
{
@@ -409,6 +415,9 @@ txg_do_callbacks(list_t *cb_list)
/*
* Dispatch the commit callbacks registered on this txg to worker threads.
+ *
+ * If no callbacks are registered for a given TXG, nothing happens.
+ * This function creates a taskq for the associated pool, if needed.
*/
static void
txg_dispatch_callbacks(dsl_pool_t *dp, uint64_t txg)
@@ -419,7 +428,10 @@ txg_dispatch_callbacks(dsl_pool_t *dp, uint64_t txg)
for (c = 0; c < max_ncpus; c++) {
tx_cpu_t *tc = &tx->tx_cpu[c];
- /* No need to lock tx_cpu_t at this point */
+ /*
+ * No need to lock tx_cpu_t at this point, since this can
+ * only be called once a txg has been synced.
+ */
int g = txg & TXG_MASK;
diff --git a/module/zfs/vdev_label.c b/module/zfs/vdev_label.c
index 07e66ebdc..0405608c2 100644
--- a/module/zfs/vdev_label.c
+++ b/module/zfs/vdev_label.c
@@ -1035,6 +1035,7 @@ vdev_uberblock_sync(zio_t *zio, uberblock_t *ub, vdev_t *vd, int flags)
zio_buf_free(ubbuf, VDEV_UBERBLOCK_SIZE(vd));
}
+/* Sync the uberblocks to all vdevs in svd[] */
int
vdev_uberblock_sync_list(vdev_t **svd, int svdcount, uberblock_t *ub, int flags)
{
diff --git a/module/zfs/vdev_raidz.c b/module/zfs/vdev_raidz.c
index 130ec575e..d2dfd5b43 100644
--- a/module/zfs/vdev_raidz.c
+++ b/module/zfs/vdev_raidz.c
@@ -431,23 +431,50 @@ static const zio_vsd_ops_t vdev_raidz_vsd_ops = {
vdev_raidz_cksum_report
};
+/*
+ * Divides the IO evenly across all child vdevs; usually, dcols is
+ * the number of children in the target vdev.
+ */
static raidz_map_t *
vdev_raidz_map_alloc(zio_t *zio, uint64_t unit_shift, uint64_t dcols,
uint64_t nparity)
{
raidz_map_t *rm;
+ /* The starting RAIDZ (parent) vdev sector of the block. */
uint64_t b = zio->io_offset >> unit_shift;
+ /* The zio's size in units of the vdev's minimum sector size. */
uint64_t s = zio->io_size >> unit_shift;
+ /* The first column for this stripe. */
uint64_t f = b % dcols;
+ /* The starting byte offset on each child vdev. */
uint64_t o = (b / dcols) << unit_shift;
uint64_t q, r, c, bc, col, acols, scols, coff, devidx, asize, tot;
+ /*
+ * "Quotient": The number of data sectors for this stripe on all but
+ * the "big column" child vdevs that also contain "remainder" data.
+ */
q = s / (dcols - nparity);
+
+ /*
+ * "Remainder": The number of partial stripe data sectors in this I/O.
+ * This will add a sector to some, but not all, child vdevs.
+ */
r = s - q * (dcols - nparity);
+
+ /* The number of "big columns" - those which contain remainder data. */
bc = (r == 0 ? 0 : r + nparity);
+
+ /*
+ * The total number of data and parity sectors associated with
+ * this I/O.
+ */
tot = s + nparity * (q + (r == 0 ? 0 : 1));
+ /* acols: The columns that will be accessed. */
+ /* scols: The columns that will be accessed or skipped. */
if (q == 0) {
+ /* Our I/O request doesn't span all child vdevs. */
acols = bc;
scols = MIN(dcols, roundup(bc, nparity + 1));
} else {
@@ -1521,6 +1548,23 @@ vdev_raidz_child_done(zio_t *zio)
rc->rc_skipped = 0;
}
+/*
+ * Start an IO operation on a RAIDZ VDev
+ *
+ * Outline:
+ * - For write operations:
+ * 1. Generate the parity data
+ * 2. Create child zio write operations to each column's vdev, for both
+ * data and parity.
+ * 3. If the column skips any sectors for padding, create optional dummy
+ * write zio children for those areas to improve aggregation continuity.
+ * - For read operations:
+ * 1. Create child zio read operations to each data column's vdev to read
+ * the range of data required for zio.
+ * 2. If this is a scrub or resilver operation, or if any of the data
+ * vdevs have had errors, then create zio read operations to the parity
+ * columns' VDevs as well.
+ */
static int
vdev_raidz_io_start(zio_t *zio)
{
@@ -1864,6 +1908,27 @@ done:
return (ret);
}
+/*
+ * Complete an IO operation on a RAIDZ VDev
+ *
+ * Outline:
+ * - For write operations:
+ * 1. Check for errors on the child IOs.
+ * 2. Return, setting an error code if too few child VDevs were written
+ * to reconstruct the data later. Note that partial writes are
+ * considered successful if they can be reconstructed at all.
+ * - For read operations:
+ * 1. Check for errors on the child IOs.
+ * 2. If data errors occurred:
+ * a. Try to reassemble the data from the parity available.
+ * b. If we haven't yet read the parity drives, read them now.
+ * c. If all parity drives have been read but the data still doesn't
+ * reassemble with a correct checksum, then try combinatorial
+ * reconstruction.
+ * d. If that doesn't work, return an error.
+ * 3. If there were unexpected errors or this is a resilver operation,
+ * rewrite the vdevs that had errors.
+ */
static void
vdev_raidz_io_done(zio_t *zio)
{
diff --git a/module/zfs/zfs_ctldir.c b/module/zfs/zfs_ctldir.c
index ce084fff1..c08e9dd9b 100644
--- a/module/zfs/zfs_ctldir.c
+++ b/module/zfs/zfs_ctldir.c
@@ -368,6 +368,11 @@ zfsctl_snapshot_zname(struct inode *ip, const char *name, int len, char *zname)
return (0);
}
+/*
+ * Gets the full dataset name that corresponds to the given snapshot name
+ * Example:
+ * zfsctl_snapshot_zname("snap1") -> "mypool/myfs@snap1"
+ */
static int
zfsctl_snapshot_zpath(struct path *path, int len, char *zpath)
{
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-15 02:02:41 +0000