From 99c8c0b03a3368d81756440ab48091e1f2430a5f Mon Sep 17 00:00:00 2001 From: Krutika Dhananjay Date: Thu, 6 Apr 2017 18:10:41 +0530 Subject: features/shard: Fix vm corruption upon fix-layout shard's writev implementation, as part of identifying presence of participant shards that aren't in memory, first sends an MKNOD on these shards, and upon EEXIST error, looks up the shards before proceeding with the writes. The VM corruption was caused when the following happened: 1. DHT had n subvolumes initially. 2. Upon add-brick + fix-layout, the layout of .shard changed although the existing shards under it were yet to be migrated to their new hashed subvolumes. 3. During this time, there were writes on the VM falling in regions of the file whose corresponding shards were already existing under .shard. 4. Sharding xl sent MKNOD on these shards, now creating them in their new hashed subvolumes although there already exist shard blocks for this region with valid data. 5. All subsequent writes were wound on these newly created copies. The net outcome is that both copies of the shard didn't have the correct data. This caused the affected VMs to be unbootable. FIX: For want of better alternatives in DHT, the fix changes shard fops to do a LOOKUP before the MKNOD and upon EEXIST error, perform another lookup. Change-Id: I8a2e97d91ba3275fbc7174a008c7234fa5295d36 BUG: 1440051 RCA'd-by: Raghavendra Gowdappa Reported-by: Mahdi Adnan Signed-off-by: Krutika Dhananjay Reviewed-on: https://review.gluster.org/17010 Smoke: Gluster Build System Reviewed-by: Pranith Kumar Karampuri NetBSD-regression: NetBSD Build System CentOS-regression: Gluster Build System --- xlators/features/shard/src/shard.c | 154 +++++++++++++++++++++++-------------- xlators/features/shard/src/shard.h | 1 + 2 files changed, 96 insertions(+), 59 deletions(-) diff --git a/xlators/features/shard/src/shard.c b/xlators/features/shard/src/shard.c index 074a497d0dc..e35bec7d1a3 100644 --- a/xlators/features/shard/src/shard.c +++ b/xlators/features/shard/src/shard.c @@ -1693,11 +1693,30 @@ shard_common_lookup_shards_cbk (call_frame_t *frame, void *cookie, if (op_ret < 0) { /* Ignore absence of shards in the backend in truncate fop. */ - if (((local->fop == GF_FOP_TRUNCATE) || - (local->fop == GF_FOP_FTRUNCATE) || - (local->fop == GF_FOP_RENAME) || - (local->fop == GF_FOP_UNLINK)) && (op_errno == ENOENT)) - goto done; + switch (local->fop) { + case GF_FOP_TRUNCATE: + case GF_FOP_FTRUNCATE: + case GF_FOP_RENAME: + case GF_FOP_UNLINK: + if (op_errno == ENOENT) + goto done; + break; + case GF_FOP_WRITE: + case GF_FOP_READ: + case GF_FOP_ZEROFILL: + case GF_FOP_DISCARD: + case GF_FOP_FALLOCATE: + if ((!local->first_lookup_done) && + (op_errno == ENOENT)) { + local->create_count++; + goto done; + } + break; + default: + break; + } + + /* else */ gf_msg (this->name, GF_LOG_ERROR, op_errno, SHARD_MSG_LOOKUP_SHARD_FAILED, "Lookup on shard %d " "failed. Base file gfid = %s", shard_block_num, @@ -1714,6 +1733,8 @@ shard_common_lookup_shards_cbk (call_frame_t *frame, void *cookie, done: call_count = shard_call_count_return (frame); if (call_count == 0) { + if (!local->first_lookup_done) + local->first_lookup_done = _gf_true; if (local->op_ret < 0) goto unwind; else @@ -3193,47 +3214,6 @@ next: return 0; } -int -shard_post_lookup_shards_readv_handler (call_frame_t *frame, xlator_t *this) -{ - shard_local_t *local = NULL; - - local = frame->local; - - if (local->op_ret < 0) { - SHARD_STACK_UNWIND (readv, frame, local->op_ret, - local->op_errno, NULL, 0, NULL, NULL, NULL); - return 0; - } - - shard_readv_do (frame, this); - - return 0; -} - -int -shard_post_mknod_readv_handler (call_frame_t *frame, xlator_t *this) -{ - shard_local_t *local = NULL; - - local = frame->local; - - if (local->op_ret < 0) { - SHARD_STACK_UNWIND (readv, frame, local->op_ret, - local->op_errno, NULL, 0, NULL, NULL, NULL); - return 0; - } - - if (!local->eexist_count) { - shard_readv_do (frame, this); - } else { - local->call_count = local->eexist_count; - shard_common_lookup_shards (frame, this, local->loc.inode, - shard_post_lookup_shards_readv_handler); - } - return 0; -} - int shard_common_mknod_cbk (call_frame_t *frame, void *cookie, xlator_t *this, int32_t op_ret, int32_t op_errno, inode_t *inode, @@ -3264,6 +3244,7 @@ done: call_count = shard_call_count_return (frame); if (call_count == 0) { SHARD_UNSET_ROOT_FS_ID (frame, local); + local->create_count = 0; local->post_mknod_handler (frame, this); } @@ -3393,6 +3374,55 @@ err: return 0; } +int +shard_post_mknod_readv_handler (call_frame_t *frame, xlator_t *this); + +int +shard_post_lookup_shards_readv_handler (call_frame_t *frame, xlator_t *this) +{ + shard_local_t *local = NULL; + + local = frame->local; + + if (local->op_ret < 0) { + SHARD_STACK_UNWIND (readv, frame, local->op_ret, + local->op_errno, NULL, 0, NULL, NULL, NULL); + return 0; + } + + if (local->create_count) { + shard_common_resume_mknod (frame, this, + shard_post_mknod_readv_handler); + } else { + shard_readv_do (frame, this); + } + + return 0; +} + +int +shard_post_mknod_readv_handler (call_frame_t *frame, xlator_t *this) +{ + shard_local_t *local = NULL; + + local = frame->local; + + if (local->op_ret < 0) { + SHARD_STACK_UNWIND (readv, frame, local->op_ret, + local->op_errno, NULL, 0, NULL, NULL, NULL); + return 0; + } + + if (!local->eexist_count) { + shard_readv_do (frame, this); + } else { + local->call_count = local->eexist_count; + shard_common_lookup_shards (frame, this, local->loc.inode, + shard_post_lookup_shards_readv_handler); + } + return 0; +} + int shard_post_resolve_readv_handler (call_frame_t *frame, xlator_t *this) { @@ -3419,9 +3449,9 @@ shard_post_resolve_readv_handler (call_frame_t *frame, xlator_t *this) } if (local->call_count) { - local->create_count = local->call_count; - shard_common_resume_mknod (frame, this, - shard_post_mknod_readv_handler); + shard_common_lookup_shards (frame, this, + local->resolver_base_inode, + shard_post_lookup_shards_readv_handler); } else { shard_readv_do (frame, this); } @@ -3572,14 +3602,11 @@ shard_readv (call_frame_t *frame, xlator_t *this, fd_t *fd, size_t size, shard_lookup_base_file (frame, this, &local->loc, shard_post_lookup_readv_handler); - return 0; - err: SHARD_STACK_UNWIND (readv, frame, -1, ENOMEM, NULL, 0, NULL, NULL, NULL); return 0; - } int @@ -3871,6 +3898,10 @@ next: return 0; } +int +shard_common_inode_write_post_mknod_handler (call_frame_t *frame, + xlator_t *this); + int shard_common_inode_write_post_lookup_shards_handler (call_frame_t *frame, xlator_t *this) @@ -3886,7 +3917,12 @@ shard_common_inode_write_post_lookup_shards_handler (call_frame_t *frame, return 0; } - shard_common_inode_write_do (frame, this); + if (local->create_count) { + shard_common_resume_mknod (frame, this, + shard_common_inode_write_post_mknod_handler); + } else { + shard_common_inode_write_do (frame, this); + } return 0; } @@ -3934,11 +3970,13 @@ shard_common_inode_write_post_lookup_handler (call_frame_t *frame, local->postbuf = local->prebuf; - if (local->create_count) - shard_common_resume_mknod (frame, this, - shard_common_inode_write_post_mknod_handler); - else + if (local->call_count) { + shard_common_lookup_shards (frame, this, + local->resolver_base_inode, + shard_common_inode_write_post_lookup_shards_handler); + } else { shard_common_inode_write_do (frame, this); + } return 0; } @@ -3958,8 +3996,6 @@ shard_common_inode_write_post_resolve_handler (call_frame_t *frame, return 0; } - local->create_count = local->call_count; - shard_lookup_base_file (frame, this, &local->loc, shard_common_inode_write_post_lookup_handler); return 0; diff --git a/xlators/features/shard/src/shard.h b/xlators/features/shard/src/shard.h index 09232a45f24..73195983aa4 100644 --- a/xlators/features/shard/src/shard.h +++ b/xlators/features/shard/src/shard.h @@ -255,6 +255,7 @@ typedef struct shard_local { shard_lock_t *shard_lock; } lock; inode_t *resolver_base_inode; + gf_boolean_t first_lookup_done; } shard_local_t; typedef struct shard_inode_ctx { -- cgit