[PATCH 4.2 077/134] NFSv4.1/pnfs: Fix atomicity of commit list updates

Greg Kroah-Hartman
2015-09-26T21:00:10Z

From: Trond Myklebust <trond.myklebust@primarydata.com>

commit 86d80f973434de24d8a807a92cd59d5ced7bd519 upstream.

pnfs_layout_mark_request_commit() needs to ensure that it adds the
request to the commit list atomically with all the other updates
in order to prevent corruption to buckets[ds_commit_idx].wlseg
due to races with pnfs_generic_clear_request_commit().

Fixes: 338d00cfef07d ("pnfs: Refactor the *_layout_mark_request_commit...")
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/nfs/internal.h | 15 ++++++++++-----
fs/nfs/pnfs_nfs.c | 5 +++--
fs/nfs/write.c | 29 ++++++++++++++++++++++++-----
3 files changed, 37 insertions(+), 12 deletions(-)

--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -490,6 +490,9 @@ void nfs_retry_commit(struct list_head *
void nfs_commitdata_release(struct nfs_commit_data *data);
void nfs_request_add_commit_list(struct nfs_page *req, struct list_head *dst,
struct nfs_commit_info *cinfo);
+void nfs_request_add_commit_list_locked(struct nfs_page *req,
+ struct list_head *dst,
+ struct nfs_commit_info *cinfo);
void nfs_request_remove_commit_list(struct nfs_page *req,
struct nfs_commit_info *cinfo);
void nfs_init_cinfo(struct nfs_commit_info *cinfo,
@@ -623,13 +626,15 @@ void nfs_super_set_maxbytes(struct super
* Record the page as unstable and mark its inode as dirty.
*/
static inline
-void nfs_mark_page_unstable(struct page *page)
+void nfs_mark_page_unstable(struct page *page, struct nfs_commit_info *cinfo)
{
- struct inode *inode = page_file_mapping(page)->host;
+ if (!cinfo->dreq) {
+ struct inode *inode = page_file_mapping(page)->host;

- inc_zone_page_state(page, NR_UNSTABLE_NFS);
- inc_wb_stat(&inode_to_bdi(inode)->wb, WB_RECLAIMABLE);
- __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
+ inc_zone_page_state(page, NR_UNSTABLE_NFS);
+ inc_wb_stat(&inode_to_bdi(inode)->wb, WB_RECLAIMABLE);
+ __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
+ }
}

/*
--- a/fs/nfs/pnfs_nfs.c
+++ b/fs/nfs/pnfs_nfs.c
@@ -863,9 +863,10 @@ pnfs_layout_mark_request_commit(struct n
}
set_bit(PG_COMMIT_TO_DS, &req->wb_flags);
cinfo->ds->nwritten++;
- spin_unlock(cinfo->lock);

- nfs_request_add_commit_list(req, list, cinfo);
+ nfs_request_add_commit_list_locked(req, list, cinfo);
+ spin_unlock(cinfo->lock);
+ nfs_mark_page_unstable(req->wb_page, cinfo);
}
EXPORT_SYMBOL_GPL(pnfs_layout_mark_request_commit);

--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -768,6 +768,28 @@ nfs_page_search_commits_for_head_request
}

/**
+ * nfs_request_add_commit_list_locked - add request to a commit list
+ * @req: pointer to a struct nfs_page
+ * @dst: commit list head
+ * @cinfo: holds list lock and accounting info
+ *
+ * This sets the PG_CLEAN bit, updates the cinfo count of
+ * number of outstanding requests requiring a commit as well as
+ * the MM page stats.
+ *
+ * The caller must hold the cinfo->lock, and the nfs_page lock.
+ */
+void
+nfs_request_add_commit_list_locked(struct nfs_page *req, struct list_head *dst,
+ struct nfs_commit_info *cinfo)
+{
+ set_bit(PG_CLEAN, &req->wb_flags);
+ nfs_list_add_request(req, dst);
+ cinfo->mds->ncommit++;
+}
+EXPORT_SYMBOL_GPL(nfs_request_add_commit_list_locked);
+
+/**
* nfs_request_add_commit_list - add request to a commit list
* @req: pointer to a struct nfs_page
* @dst: commit list head
@@ -784,13 +806,10 @@ void
nfs_request_add_commit_list(struct nfs_page *req, struct list_head *dst,
struct nfs_commit_info *cinfo)
{
- set_bit(PG_CLEAN, &(req)->wb_flags);
spin_lock(cinfo->lock);
- nfs_list_add_request(req, dst);
- cinfo->mds->ncommit++;
+ nfs_request_add_commit_list_locked(req, dst, cinfo);
spin_unlock(cinfo->lock);
- if (!cinfo->dreq)
- nfs_mark_page_unstable(req->wb_page);
+ nfs_mark_page_unstable(req->wb_page, cinfo);
}
EXPORT_SYMBOL_GPL(nfs_request_add_commit_list);