pnfs: fix race in filelayout commit path
Hold the lock while modifying commit info dataserver buckets. The following oops can be reproduced by running iozone for a while against a 2 DS pynfs filelayout server. general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC Modules linked in: nfs_layout_nfsv41_files rpcsec_gss_krb5 nfsv4 nfs fscache CPU: 0 PID: 903 Comm: iozone Not tainted 3.15.0-rc1-branch-dros_testing+ #44 Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference task: ffff880078164480 ti: ffff88006e972000 task.ti: ffff88006e972000 RIP: 0010:[<ffffffffa01936e1>] [<ffffffffa01936e1>] nfs_init_commit+0x22/0x RSP: 0018:ffff88006e973d30 EFLAGS: 00010246 RAX: ffff88006e973e00 RBX: ffff88006e828800 RCX: ffff88006e973e10 RDX: 0000000000000000 RSI: ffff88006e973e00 RDI: dead4ead00000000 RBP: ffff88006e973d38 R08: ffff88006e8289d8 R09: 0000000000000000 R10: ffff88006e8289d8 R11: 0000000000016988 R12: ffff88006e973b98 R13: ffff88007a0a6648 R14: ffff88006e973e10 R15: ffff88006e828800 FS: 00007f2ce396b740(0000) GS:ffff88007f200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f03278a1000 CR3: 0000000079043000 CR4: 00000000001407f0 Stack: ffff88006e8289d8 ffff88006e973da8 ffffffffa00f144f ffff88006e9478c0 ffff88006e973e00 ffff88006de21080 0000000100000002 ffff880079be6c48 ffff88006e973d70 ffff88006e973d70 ffff88006e973e10 ffff88006de21080 Call Trace: [<ffffffffa00f144f>] filelayout_commit_pagelist+0x1ae/0x34a [nfs_layout_nfsv [<ffffffffa0194f72>] nfs_generic_commit_list+0x92/0xc4 [nfs] [<ffffffffa0195053>] nfs_commit_inode+0xaf/0x114 [nfs] [<ffffffffa01892bd>] nfs_file_fsync_commit+0x82/0xbe [nfs] [<ffffffffa01ceb0d>] nfs4_file_fsync+0x59/0x9b [nfsv4] [<ffffffff8114ee3c>] vfs_fsync_range+0x18/0x20 [<ffffffff8114ee60>] vfs_fsync+0x1c/0x1e [<ffffffffa01891c2>] nfs_file_flush+0x7f/0x84 [nfs] [<ffffffff81127a43>] filp_close+0x3c/0x72 [<ffffffff81140e12>] __close_fd+0x82/0x9a [<ffffffff81127a9c>] SyS_close+0x23/0x4c [<ffffffff814acd12>] system_call_fastpath+0x16/0x1b Code: 5b 41 5c 41 5d 41 5e 5d c3 0f 1f 44 00 00 55 48 89 e5 53 48 89 fb 48 8 RIP [<ffffffffa01936e1>] nfs_init_commit+0x22/0xe1 [nfs] RSP <ffff88006e973d30> ---[ end trace 732fe6419b235e2f ]--- Suggested-by: Trond Myklebust <trond.myklebust@primarydata.com> Signed-off-by: Weston Andros Adamson <dros@primarydata.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
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41d8d5b7a5
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d201c4de51
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@ -1067,6 +1067,7 @@ filelayout_choose_commit_list(struct nfs_page *req,
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*/
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j = nfs4_fl_calc_j_index(lseg, req_offset(req));
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i = select_bucket_index(fl, j);
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spin_lock(cinfo->lock);
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buckets = cinfo->ds->buckets;
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list = &buckets[i].written;
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if (list_empty(list)) {
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@ -1080,6 +1081,7 @@ filelayout_choose_commit_list(struct nfs_page *req,
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}
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set_bit(PG_COMMIT_TO_DS, &req->wb_flags);
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cinfo->ds->nwritten++;
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spin_unlock(cinfo->lock);
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return list;
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}
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@ -1176,6 +1178,7 @@ transfer_commit_list(struct list_head *src, struct list_head *dst,
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return ret;
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}
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/* Note called with cinfo->lock held. */
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static int
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filelayout_scan_ds_commit_list(struct pnfs_commit_bucket *bucket,
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struct nfs_commit_info *cinfo,
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@ -1220,15 +1223,18 @@ static void filelayout_recover_commit_reqs(struct list_head *dst,
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struct nfs_commit_info *cinfo)
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{
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struct pnfs_commit_bucket *b;
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struct pnfs_layout_segment *freeme;
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int i;
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restart:
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spin_lock(cinfo->lock);
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for (i = 0, b = cinfo->ds->buckets; i < cinfo->ds->nbuckets; i++, b++) {
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if (transfer_commit_list(&b->written, dst, cinfo, 0)) {
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spin_unlock(cinfo->lock);
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pnfs_put_lseg(b->wlseg);
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freeme = b->wlseg;
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b->wlseg = NULL;
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spin_lock(cinfo->lock);
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spin_unlock(cinfo->lock);
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pnfs_put_lseg(freeme);
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goto restart;
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}
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}
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cinfo->ds->nwritten = 0;
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@ -1243,6 +1249,7 @@ alloc_ds_commits(struct nfs_commit_info *cinfo, struct list_head *list)
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struct nfs_commit_data *data;
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int i, j;
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unsigned int nreq = 0;
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struct pnfs_layout_segment *freeme;
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fl_cinfo = cinfo->ds;
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bucket = fl_cinfo->buckets;
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@ -1253,8 +1260,10 @@ alloc_ds_commits(struct nfs_commit_info *cinfo, struct list_head *list)
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if (!data)
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break;
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data->ds_commit_index = i;
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spin_lock(cinfo->lock);
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data->lseg = bucket->clseg;
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bucket->clseg = NULL;
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spin_unlock(cinfo->lock);
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list_add(&data->pages, list);
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nreq++;
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}
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@ -1264,8 +1273,11 @@ alloc_ds_commits(struct nfs_commit_info *cinfo, struct list_head *list)
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if (list_empty(&bucket->committing))
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continue;
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nfs_retry_commit(&bucket->committing, bucket->clseg, cinfo);
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pnfs_put_lseg(bucket->clseg);
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spin_lock(cinfo->lock);
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freeme = bucket->clseg;
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bucket->clseg = NULL;
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spin_unlock(cinfo->lock);
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pnfs_put_lseg(freeme);
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}
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/* Caller will clean up entries put on list */
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return nreq;
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