2014-07-03 05:08:09

by Peng Tao

[permalink] [raw]
Subject: [PATCH 1/2] pnfs/filelayout: fix race between mark_request_commit and scan_commit_lists

We need to hold cinfo lock while setting bucket->wlseg and adding req to nwritten
list at the same time. Otherwise there might be a window where nwritten list
is empty yet we set bucket->wlseg, in which case ff_layout_scan_ds_commit_list()
may end up clearing bucket->wlseg incorrectly, casuing client to oops later on.

This was found when testing flexfile layout but filelayout has the same problem.

Signed-off-by: Peng Tao <[email protected]>
Signed-off-by: Tom Haynes <[email protected]>
---
fs/nfs/filelayout/filelayout.c | 43 ++++++++++++++++++++++++------------------
1 file changed, 25 insertions(+), 18 deletions(-)

diff --git a/fs/nfs/filelayout/filelayout.c b/fs/nfs/filelayout/filelayout.c
index 504d58a..a928f92 100644
--- a/fs/nfs/filelayout/filelayout.c
+++ b/fs/nfs/filelayout/filelayout.c
@@ -1035,18 +1035,22 @@ out:
pnfs_put_lseg(freeme);
}

-static struct list_head *
-filelayout_choose_commit_list(struct nfs_page *req,
- struct pnfs_layout_segment *lseg,
- struct nfs_commit_info *cinfo)
+static void
+filelayout_mark_request_commit(struct nfs_page *req,
+ struct pnfs_layout_segment *lseg,
+ struct nfs_commit_info *cinfo)
+
{
struct nfs4_filelayout_segment *fl = FILELAYOUT_LSEG(lseg);
u32 i, j;
struct list_head *list;
struct pnfs_commit_bucket *buckets;

- if (fl->commit_through_mds)
- return &cinfo->mds->list;
+ if (fl->commit_through_mds) {
+ list = &cinfo->mds->list;
+ spin_lock(cinfo->lock);
+ goto mds_commit;
+ }

/* Note that we are calling nfs4_fl_calc_j_index on each page
* that ends up being committed to a data server. An attractive
@@ -1070,19 +1074,22 @@ filelayout_choose_commit_list(struct nfs_page *req,
}
set_bit(PG_COMMIT_TO_DS, &req->wb_flags);
cinfo->ds->nwritten++;
- spin_unlock(cinfo->lock);
- return list;
-}

-static void
-filelayout_mark_request_commit(struct nfs_page *req,
- struct pnfs_layout_segment *lseg,
- struct nfs_commit_info *cinfo)
-{
- struct list_head *list;
-
- list = filelayout_choose_commit_list(req, lseg, cinfo);
- nfs_request_add_commit_list(req, list, cinfo);
+mds_commit:
+ /* nfs_request_add_commit_list(). We need to add req to list without
+ * dropping cinfo lock.
+ */
+ set_bit(PG_CLEAN, &(req)->wb_flags);
+ nfs_list_add_request(req, list);
+ cinfo->mds->ncommit++;
+ spin_unlock(cinfo->lock);
+ if (!cinfo->dreq) {
+ inc_zone_page_state(req->wb_page, NR_UNSTABLE_NFS);
+ inc_bdi_stat(page_file_mapping(req->wb_page)->backing_dev_info,
+ BDI_RECLAIMABLE);
+ __mark_inode_dirty(req->wb_context->dentry->d_inode,
+ I_DIRTY_DATASYNC);
+ }
}

static u32 calc_ds_index_from_commit(struct pnfs_layout_segment *lseg, u32 i)
--
1.9.1



2014-07-03 05:08:15

by Peng Tao

[permalink] [raw]
Subject: [PATCH 2/2] pnfs/filelayout: retry ds commit if nfs_commitdata_alloc fails

Signed-off-by: Peng Tao <[email protected]>
Signed-off-by: Tom Haynes <[email protected]>
---
fs/nfs/filelayout/filelayout.c | 39 ++++++++++++++++++++++++++-------------
1 file changed, 26 insertions(+), 13 deletions(-)

diff --git a/fs/nfs/filelayout/filelayout.c b/fs/nfs/filelayout/filelayout.c
index a928f92..2576d28b 100644
--- a/fs/nfs/filelayout/filelayout.c
+++ b/fs/nfs/filelayout/filelayout.c
@@ -1237,15 +1237,33 @@ restart:
spin_unlock(cinfo->lock);
}

+static void filelayout_retry_commit(struct nfs_commit_info *cinfo, int idx)
+{
+ struct pnfs_ds_commit_info *fl_cinfo = cinfo->ds;
+ struct pnfs_commit_bucket *bucket = fl_cinfo->buckets;
+ struct pnfs_layout_segment *freeme;
+ int i;
+
+ for (i = idx; i < fl_cinfo->nbuckets; i++, bucket++) {
+ if (list_empty(&bucket->committing))
+ continue;
+ nfs_retry_commit(&bucket->committing, bucket->clseg, cinfo);
+ spin_lock(cinfo->lock);
+ freeme = bucket->clseg;
+ bucket->clseg = NULL;
+ spin_unlock(cinfo->lock);
+ pnfs_put_lseg(freeme);
+ }
+}
+
static unsigned int
alloc_ds_commits(struct nfs_commit_info *cinfo, struct list_head *list)
{
struct pnfs_ds_commit_info *fl_cinfo;
struct pnfs_commit_bucket *bucket;
struct nfs_commit_data *data;
- int i, j;
+ int i;
unsigned int nreq = 0;
- struct pnfs_layout_segment *freeme;

fl_cinfo = cinfo->ds;
bucket = fl_cinfo->buckets;
@@ -1265,16 +1283,7 @@ alloc_ds_commits(struct nfs_commit_info *cinfo, struct list_head *list)
}

/* Clean up on error */
- for (j = i; j < fl_cinfo->nbuckets; j++, bucket++) {
- if (list_empty(&bucket->committing))
- continue;
- nfs_retry_commit(&bucket->committing, bucket->clseg, cinfo);
- spin_lock(cinfo->lock);
- freeme = bucket->clseg;
- bucket->clseg = NULL;
- spin_unlock(cinfo->lock);
- pnfs_put_lseg(freeme);
- }
+ filelayout_retry_commit(cinfo, i);
/* Caller will clean up entries put on list */
return nreq;
}
@@ -1294,8 +1303,12 @@ filelayout_commit_pagelist(struct inode *inode, struct list_head *mds_pages,
data->lseg = NULL;
list_add(&data->pages, &list);
nreq++;
- } else
+ } else {
nfs_retry_commit(mds_pages, NULL, cinfo);
+ filelayout_retry_commit(cinfo, 0);
+ cinfo->completion_ops->error_cleanup(NFS_I(inode));
+ return -ENOMEM;
+ }
}

nreq += alloc_ds_commits(cinfo, &list);
--
1.9.1