[Crash-utility] Re: [PATCH v6 3/4] xarray: add large folio support

We may meet a large folio at two cases: 1.) when height is 1, the real data layout may looks like this: -------------------------------------------- crash> p *(struct xa_node*)0xffff889883a6a910 $5 = { shift = 0 '\000', offset = 0 '\000', count = 64 '@', nr_values = 0 '\000', ................. slots = { 0xffffea0061d21000, 0x2, 0x2, 0x2, 0xffffea0121d85c00, 0x12, 0x12, 0x12, 0xffffea0121d9f400, 0x22, 0x22, 0x22, 0x22, 0x22, 0x22, 0x22, 0xffffea0121583800, 0x42, 0x42, 0x42, 0x42, 0x42, 0x42, 0x42, 0xffffea0121833e00, 0x62, 0x62, 0x62, 0x62, 0x62, 0x62, 0x62, 0xffffea0121eb3800, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82, 0x82 }, ................. } -------------------------------------------- The page orders for above folios: 0xffffea0061d21000 --> order 2 0xffffea0121d85c00 --> order 2 0xffffea0121d9f400 --> order 3 0xffffea0121583800 --> order 3 0xffffea0121833e00 --> order 3 0xffffea0121eb3800 --> order 5 2.) when height is not 1, the real data layout may looks like this: -------------------------------------------- slot: { 0xffff8a2c866b745a, 0xffff8a2c866b16d2, 0xfffff9fcc4ea4000, 0xfffff9fcc4eb9000, ..} -------------------------------------------- The 0xffff8a2c866b745a and 0xffff8a2c866b16d2 is a internal node, not a folio.

The page orders for above folios: 0xfffff9fcc4ea4000 --> order 6

Current code does not work correctly with large folio page cache. This patch adds the large folio support with following: 1.) changed the do_xarray_iter() to detect the order of a folio, and skip the proper dummy slots for a large folio. 2.) updated do_xarray_count/do_xarray_dump/do_xarray_dump_cb with correct page number if we meet a large folio. (Use folio_update_count as the hook for them) Signed-off-by: Huang Shijie <huangsj(a)hygon.cn&gt; --- filesys.c | 23 ++++++++++++++++++++--- tools.c | 16 +++++++++++++--- 2 files changed, 33 insertions(+), 6 deletions(-) diff --git a/filesys.c b/filesys.c index 1e070a3..d30aa6e 100644 --- a/filesys.c +++ b/filesys.c @@ -4217,12 +4217,24 @@ struct do_xarray_info { ulong maxcount; ulong count; void *data; + ulong (*update_count)(ulong); }; + +static ulong +folio_update_count(ulong slot) +{ + return 1 << folio_order(slot); +} + static void do_xarray_count(ulong node, ulong slot, const char *path, ulong index, void *private) { struct do_xarray_info *info = private; - info->count++; + + if (info->update_count) + info->count += info->update_count(slot); + else + info->count++; } static void do_xarray_search(ulong node, ulong slot, const char *path, ulong index, void *private) @@ -4239,8 +4251,9 @@ static void do_xarray_dump(ulong node, ulong slot, const char *path, ulong index, void *private) { struct do_xarray_info *info = private; + fprintf(fp, "[%ld] %lx\n", index, slot); - info->count++; + do_xarray_count(node, slot, path, index, private); } static void do_xarray_gather(ulong node, ulong slot, const char *path, ulong index, void *private) @@ -4274,7 +4287,8 @@ static void do_xarray_dump_cb(ulong node, ulong slot, const char *path, "operation failed: entry: %ld item: %lx\n", info->count, slot); } - info->count++; + + do_xarray_count(node, slot, path, index, private); } /* @@ -4321,6 +4335,9 @@ do_xarray(ulong root, int flag, struct list_pair *xp, int type) .private = &info, }; + if (type == XARRAY_TYPE_PAGE_CACHE) + info.update_count = folio_update_count; + switch (flag) { case XARRAY_COUNT: diff --git a/tools.c b/tools.c index 69250c4..6b51423 100644 --- a/tools.c +++ b/tools.c @@ -4737,15 +4737,19 @@ do_xarray_iter(ulong node, uint height, char *path, ulong index, struct xarray_ops *ops) { uint off; + uint order, is_folio; if (!hq_enter(node)) error(FATAL, "\nduplicate tree node: %lx\n", node); - for (off = 0; off < XA_CHUNK_SIZE; off++) { + for (off = 0; off < XA_CHUNK_SIZE; off += 1 << order) { ulong slot; ulong shift = (height - 1) * XA_CHUNK_SHIFT; + order = 0; + is_folio = 0; + readmem(node + OFFSET(xa_node_slots) + sizeof(void *) * off, KVADDR, &slot, sizeof(void *), "xa_node.slots[off]", FAULT_ON_ERROR); @@ -4754,10 +4758,16 @@ do_xarray_iter(ulong node, uint height, char *path, if ((slot & XARRAY_TAG_MASK) == XARRAY_TAG_INTERNAL) slot &= ~XARRAY_TAG_INTERNAL; + else if ((slot & XARRAY_TAG_MASK) == 0) { + if (ops->type == XARRAY_TYPE_PAGE_CACHE) + is_folio = 1; + } - if (height == 1) + if (height == 1 || is_folio) { ops->entry(node, slot, path, index | off, ops->private); - else { + if (ops->type == XARRAY_TYPE_PAGE_CACHE) + order = folio_order(slot) % XA_CHUNK_SHIFT; + } else { ulong child_index = index | (off << shift); char child_path[BUFSIZE]; sprintf(child_path, "%s/%d", path, off); -- 2.34.1