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    Subject[PATCH 4.2 077/134] NFSv4.1/pnfs: Fix atomicity of commit list updates
    Date
    4.2-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    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);




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