On Tue, 2017-12-05 at 09:51 +0800, Yan, Zheng wrote:
> Avoid i_shared_gen overflow and allow accessing i_shared_gen without
> holding i_ceph_lock (prepare for later patch)
>
> Signed-off-by: "Yan, Zheng" <zyan@xxxxxxxxxx>
> ---
> fs/ceph/caps.c | 2 +-
> fs/ceph/dir.c | 16 ++++++++--------
> fs/ceph/inode.c | 4 ++--
> fs/ceph/super.h | 5 +++--
> 4 files changed, 14 insertions(+), 13 deletions(-)
>
> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
> index 029cab713731..2b3c8b1c774c 100644
> --- a/fs/ceph/caps.c
> +++ b/fs/ceph/caps.c
> @@ -498,7 +498,7 @@ static void __check_cap_issue(struct ceph_inode_info *ci, struct ceph_cap *cap,
> */
> if ((issued & CEPH_CAP_FILE_SHARED) != (had & CEPH_CAP_FILE_SHARED)) {
> if (issued & CEPH_CAP_FILE_SHARED)
> - ci->i_shared_gen++;
> + atomic64_inc(&ci->i_shared_gen);
> if (S_ISDIR(ci->vfs_inode.i_mode)) {
> dout(" marking %p NOT complete\n", &ci->vfs_inode);
> __ceph_dir_clear_complete(ci);
> diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
> index 64afa46b211f..0a23a4d9fde8 100644
> --- a/fs/ceph/dir.c
> +++ b/fs/ceph/dir.c
> @@ -173,7 +173,7 @@ __dcache_find_get_entry(struct dentry *parent, u64 idx,
> * the MDS if/when the directory is modified).
> */
> static int __dcache_readdir(struct file *file, struct dir_context *ctx,
> - u32 shared_gen)
> + long long shared_gen)
> {
> struct ceph_file_info *fi = file->private_data;
> struct dentry *parent = file->f_path.dentry;
> @@ -184,7 +184,7 @@ static int __dcache_readdir(struct file *file, struct dir_context *ctx,
> u64 idx = 0;
> int err = 0;
>
> - dout("__dcache_readdir %p v%u at %llx\n", dir, shared_gen, ctx->pos);
> + dout("__dcache_readdir %p v%llu at %llx\n", dir, (u64)shared_gen, ctx->pos);
>
> /* search start position */
> if (ctx->pos > 2) {
> @@ -333,7 +333,7 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
> ceph_snap(inode) != CEPH_SNAPDIR &&
> __ceph_dir_is_complete_ordered(ci) &&
> __ceph_caps_issued_mask(ci, CEPH_CAP_FILE_SHARED, 1)) {
> - u32 shared_gen = ci->i_shared_gen;
> + long long shared_gen = atomic64_read(&ci->i_shared_gen);
> spin_unlock(&ci->i_ceph_lock);
> err = __dcache_readdir(file, ctx, shared_gen);
> if (err != -EAGAIN)
> @@ -751,7 +751,7 @@ static struct dentry *ceph_lookup(struct inode *dir, struct dentry *dentry,
> spin_unlock(&ci->i_ceph_lock);
> dout(" dir %p complete, -ENOENT\n", dir);
> d_add(dentry, NULL);
> - di->lease_shared_gen = ci->i_shared_gen;
> + di->lease_shared_gen = atomic64_read(&ci->i_shared_gen);
> return NULL;
> }
> spin_unlock(&ci->i_ceph_lock);
> @@ -1191,12 +1191,12 @@ static int dir_lease_is_valid(struct inode *dir, struct dentry *dentry)
> int valid = 0;
>
> spin_lock(&ci->i_ceph_lock);
> - if (ci->i_shared_gen == di->lease_shared_gen)
> + if (atomic64_read(&ci->i_shared_gen) == di->lease_shared_gen)
> valid = __ceph_caps_issued_mask(ci, CEPH_CAP_FILE_SHARED, 1);
> spin_unlock(&ci->i_ceph_lock);
> - dout("dir_lease_is_valid dir %p v%u dentry %p v%u = %d\n",
> - dir, (unsigned)ci->i_shared_gen, dentry,
> - (unsigned)di->lease_shared_gen, valid);
> + dout("dir_lease_is_valid dir %p v%llu dentry %p v%llu = %d\n",
> + dir, (u64)atomic64_read(&ci->i_shared_gen),
> + dentry, (u64)di->lease_shared_gen, valid);
> return valid;
> }
>
> diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
> index 666ad10e2b85..a9de83f012bf 100644
> --- a/fs/ceph/inode.c
> +++ b/fs/ceph/inode.c
> @@ -494,7 +494,7 @@ struct inode *ceph_alloc_inode(struct super_block *sb)
> ci->i_wrbuffer_ref = 0;
> ci->i_wrbuffer_ref_head = 0;
> atomic_set(&ci->i_filelock_ref, 0);
> - ci->i_shared_gen = 0;
> + atomic64_set(&ci->i_shared_gen, 0);
> ci->i_rdcache_gen = 0;
> ci->i_rdcache_revoking = 0;
>
> @@ -1041,7 +1041,7 @@ static void update_dentry_lease(struct dentry *dentry,
> if (ceph_snap(dir) != CEPH_NOSNAP)
> goto out_unlock;
>
> - di->lease_shared_gen = ceph_inode(dir)->i_shared_gen;
> + di->lease_shared_gen = atomic64_read(&ceph_inode(dir)->i_shared_gen);
>
> if (duration == 0)
> goto out_unlock;
> diff --git a/fs/ceph/super.h b/fs/ceph/super.h
> index 2beeec07fa76..ec301fce2556 100644
> --- a/fs/ceph/super.h
> +++ b/fs/ceph/super.h
> @@ -256,7 +256,8 @@ struct ceph_inode_xattr {
> */
> struct ceph_dentry_info {
> struct ceph_mds_session *lease_session;
> - u32 lease_gen, lease_shared_gen;
> + long long lease_shared_gen;
> + u32 lease_gen;
> u32 lease_seq;
> unsigned long lease_renew_after, lease_renew_from;
> struct list_head lru;
> @@ -353,7 +354,7 @@ struct ceph_inode_info {
> int i_rd_ref, i_rdcache_ref, i_wr_ref, i_wb_ref;
> int i_wrbuffer_ref, i_wrbuffer_ref_head;
> atomic_t i_filelock_ref;
> - u32 i_shared_gen; /* increment each time we get FILE_SHARED */
> + atomic64_t i_shared_gen; /* increment each time we get FILE_SHARED */
> u32 i_rdcache_gen; /* incremented each time we get FILE_CACHE. */
> u32 i_rdcache_revoking; /* RDCACHE gen to async invalidate, if any */
>
Looks sane enough. Do we really think that i_shared_gen overflow is a
problem? Will we have the same problem with i_rdcache_gen?
Acked-by: Jeff Layton <jlayton@xxxxxxxxxx>
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