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authorKrutika Dhananjay <kdhananj@redhat.com>2018-10-05 11:32:21 +0530
committerKrutika Dhananjay <kdhananj@redhat.com>2018-10-16 03:37:44 +0000
commite627977617dd765f6b58a70882c6acda6c6aab6e (patch)
treefa2c95c576a8ba5158e47d986547379d8426cf2e /xlators/features/shard/src/shard.c
parent76cc1ea613e038ced4bc6ae26233cb0681b63be5 (diff)
features/shard: Hold a ref on base inode when adding a shard to lru list
In __shard_update_shards_inode_list(), previously shard translator was not holding a ref on the base inode whenever a shard was added to the lru list. But if the base shard is forgotten and destroyed either by fuse due to memory pressure or due to the file being deleted at some point by a different client with this client still containing stale shards in its lru list, the client would crash at the time of locking lru_base_inode->lock owing to illegal memory access. So now the base shard is ref'd into the inode ctx of every shard that is added to lru list until it gets lru'd out. The patch also handles the case where none of the shards associated with a file that is about to be deleted are part of the LRU list and where an unlink at the beginning of the operation destroys the base inode (because there are no refkeepers) and hence all of the shards that are about to be deleted will be resolved without the existence of a base shard in-memory. This, if not handled properly, could lead to a crash. Change-Id: Ic15ca41444dd04684a9458bd4a526b1d3e160499 updates: bz#1605056 Signed-off-by: Krutika Dhananjay <kdhananj@redhat.com>
Diffstat (limited to 'xlators/features/shard/src/shard.c')
-rw-r--r--xlators/features/shard/src/shard.c48
1 files changed, 34 insertions, 14 deletions
diff --git a/xlators/features/shard/src/shard.c b/xlators/features/shard/src/shard.c
index 182678c9a64..d5f55efa0bc 100644
--- a/xlators/features/shard/src/shard.c
+++ b/xlators/features/shard/src/shard.c
@@ -650,7 +650,8 @@ out:
inode_t *
__shard_update_shards_inode_list(inode_t *linked_inode, xlator_t *this,
- inode_t *base_inode, int block_num)
+ inode_t *base_inode, int block_num,
+ uuid_t gfid)
{
char block_bname[256] = {
0,
@@ -680,10 +681,13 @@ __shard_update_shards_inode_list(inode_t *linked_inode, xlator_t *this,
inode_ref(linked_inode);
if (base_inode)
gf_uuid_copy(ctx->base_gfid, base_inode->gfid);
+ else
+ gf_uuid_copy(ctx->base_gfid, gfid);
ctx->block_num = block_num;
list_add_tail(&ctx->ilist, &priv->ilist_head);
priv->inode_count++;
- ctx->base_inode = base_inode;
+ if (base_inode)
+ ctx->base_inode = inode_ref(base_inode);
} else {
/*If on the other hand there is no available slot for this inode
* in the list, delete the lru inode from the head of the list,
@@ -701,6 +705,8 @@ __shard_update_shards_inode_list(inode_t *linked_inode, xlator_t *this,
* deleted from fsync list and fsync'd in a new frame,
* and then unlinked in memory and forgotten.
*/
+ if (!lru_base_inode)
+ goto after_fsync_check;
LOCK(&lru_base_inode->lock);
LOCK(&lru_inode->lock);
{
@@ -716,6 +722,7 @@ __shard_update_shards_inode_list(inode_t *linked_inode, xlator_t *this,
UNLOCK(&lru_inode->lock);
UNLOCK(&lru_base_inode->lock);
+ after_fsync_check:
if (!do_fsync) {
shard_make_block_bname(lru_inode_ctx->block_num,
lru_inode_ctx->base_gfid, block_bname,
@@ -728,20 +735,31 @@ __shard_update_shards_inode_list(inode_t *linked_inode, xlator_t *this,
inode_forget(lru_inode, 0);
} else {
fsync_inode = lru_inode;
- inode_unref(lru_base_inode);
+ if (lru_base_inode)
+ inode_unref(lru_base_inode);
}
/* The following unref corresponds to the ref
* held by inode_find() above.
*/
inode_unref(lru_inode);
+
+ /* The following unref corresponds to the ref held on the base shard
+ * at the time of adding shard inode to lru list
+ */
+ if (lru_base_inode)
+ inode_unref(lru_base_inode);
+
/* For as long as an inode is in lru list, we try to
* keep it alive by holding a ref on it.
*/
inode_ref(linked_inode);
if (base_inode)
gf_uuid_copy(ctx->base_gfid, base_inode->gfid);
+ else
+ gf_uuid_copy(ctx->base_gfid, gfid);
ctx->block_num = block_num;
- ctx->base_inode = base_inode;
+ if (base_inode)
+ ctx->base_inode = inode_ref(base_inode);
list_add_tail(&ctx->ilist, &priv->ilist_head);
}
} else {
@@ -1025,7 +1043,7 @@ shard_common_resolve_shards(call_frame_t *frame, xlator_t *this,
LOCK(&priv->lock);
{
fsync_inode = __shard_update_shards_inode_list(
- inode, this, res_inode, shard_idx_iter);
+ inode, this, res_inode, shard_idx_iter, gfid);
}
UNLOCK(&priv->lock);
shard_idx_iter++;
@@ -2167,7 +2185,7 @@ shard_link_block_inode(shard_local_t *local, int block_num, inode_t *inode,
LOCK(&priv->lock);
{
fsync_inode = __shard_update_shards_inode_list(
- linked_inode, this, local->loc.inode, block_num);
+ linked_inode, this, local->loc.inode, block_num, gfid);
}
UNLOCK(&priv->lock);
if (fsync_inode)
@@ -2875,17 +2893,18 @@ shard_unlink_block_inode(shard_local_t *local, int shard_block_num)
shard_inode_ctx_t *ctx = NULL;
shard_inode_ctx_t *base_ictx = NULL;
gf_boolean_t unlink_unref_forget = _gf_false;
+ int unref_base_inode = 0;
this = THIS;
priv = this->private;
inode = local->inode_list[shard_block_num - local->first_block];
- base_inode = local->resolver_base_inode;
+ shard_inode_ctx_get(inode, this, &ctx);
+ base_inode = ctx->base_inode;
if (base_inode)
gf_uuid_copy(gfid, base_inode->gfid);
else
- gf_uuid_copy(gfid, local->base_gfid);
-
+ gf_uuid_copy(gfid, ctx->base_gfid);
shard_make_block_bname(shard_block_num, gfid, block_bname,
sizeof(block_bname));
@@ -2898,17 +2917,16 @@ shard_unlink_block_inode(shard_local_t *local, int shard_block_num)
if (!list_empty(&ctx->ilist)) {
list_del_init(&ctx->ilist);
priv->inode_count--;
+ unref_base_inode++;
GF_ASSERT(priv->inode_count >= 0);
unlink_unref_forget = _gf_true;
}
if (ctx->fsync_needed) {
- if (base_inode)
- inode_unref(base_inode);
+ unref_base_inode++;
list_del_init(&ctx->to_fsync_list);
- if (base_inode) {
+ if (base_inode)
__shard_inode_ctx_get(base_inode, this, &base_ictx);
- base_ictx->fsync_count--;
- }
+ base_ictx->fsync_count--;
}
}
UNLOCK(&inode->lock);
@@ -2919,6 +2937,8 @@ shard_unlink_block_inode(shard_local_t *local, int shard_block_num)
inode_unref(inode);
inode_forget(inode, 0);
}
+ if (base_inode && unref_base_inode)
+ inode_ref_reduce_by_n(base_inode, unref_base_inode);
UNLOCK(&priv->lock);
}