ceph: use i_release_count to indicate dir's completeness

Current ceph code tracks directory's completeness in two places.
ceph_readdir() checks i_release_count to decide if it can set the
I_COMPLETE flag in i_ceph_flags. All other places check the I_COMPLETE
flag. This indirection introduces locking complexity.

This patch adds a new variable i_complete_count to ceph_inode_info.
Set i_release_count's value to it when marking a directory complete.
By comparing the two variables, we know if a directory is complete

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>

5 files changed, 45 insertions, 49 deletions

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index bc575a4a813e..f9563108d189 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -490,7 +490,7 @@ static void __check_cap_issue(struct ceph_inode_info *ci, struct ceph_cap *cap,
                 ci->i_rdcache_gen++;
 
         /*
-         * if we are newly issued FILE_SHARED, clear I_COMPLETE; we
+         * if we are newly issued FILE_SHARED, mark dir not complete; we
          * don't know what happened to this directory while we didn't
          * have the cap.
          */
@@ -499,7 +499,7 @@ static void __check_cap_issue(struct ceph_inode_info *ci, struct ceph_cap *cap,
                 ci->i_shared_gen++;
                 if (S_ISDIR(ci->vfs_inode.i_mode)) {
                         dout(" marking %p NOT complete\n", &ci->vfs_inode);
-                        ci->i_ceph_flags &= ~CEPH_I_COMPLETE;
+                        __ceph_dir_clear_complete(ci);
                 }
         }
 }
diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index 0c369ac62c07..f02d82b7933e 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -107,7 +107,7 @@ static unsigned fpos_off(loff_t p)
  * falling back to a "normal" sync readdir if any dentries in the dir
  * are dropped.
  *
- * I_COMPLETE tells indicates we have all dentries in the dir.  It is
+ * Complete dir indicates that we have all dentries in the dir.  It is
  * defined IFF we hold CEPH_CAP_FILE_SHARED (which will be revoked by
  * the MDS if/when the directory is modified).
  */
@@ -198,8 +198,8 @@ more:
         filp->f_pos++;
 
         /* make sure a dentry wasn't dropped while we didn't have parent lock */
-        if (!ceph_i_test(dir, CEPH_I_COMPLETE)) {
-                dout(" lost I_COMPLETE on %p; falling back to mds\n", dir);
+        if (!ceph_dir_is_complete(dir)) {
+                dout(" lost dir complete on %p; falling back to mds\n", dir);
                 err = -EAGAIN;
                 goto out;
         }
@@ -258,7 +258,7 @@ static int ceph_readdir(struct file *filp, void *dirent, filldir_t filldir)
         if (filp->f_pos == 0) {
                 /* note dir version at start of readdir so we can tell
                  * if any dentries get dropped */
-                fi->dir_release_count = ci->i_release_count;
+                fi->dir_release_count = atomic_read(&ci->i_release_count);
 
                 dout("readdir off 0 -> '.'\n");
                 if (filldir(dirent, ".", 1, ceph_make_fpos(0, 0),
@@ -284,7 +284,7 @@ static int ceph_readdir(struct file *filp, void *dirent, filldir_t filldir)
         if ((filp->f_pos == 2 || fi->dentry) &&
             !ceph_test_mount_opt(fsc, NOASYNCREADDIR) &&
             ceph_snap(inode) != CEPH_SNAPDIR &&
-            (ci->i_ceph_flags & CEPH_I_COMPLETE) &&
+            __ceph_dir_is_complete(ci) &&
             __ceph_caps_issued_mask(ci, CEPH_CAP_FILE_SHARED, 1)) {
                 spin_unlock(&ci->i_ceph_lock);
                 err = __dcache_readdir(filp, dirent, filldir);
@@ -350,7 +350,8 @@ more:
 
                 if (!req->r_did_prepopulate) {
                         dout("readdir !did_prepopulate");
-                        fi->dir_release_count--;    /* preclude I_COMPLETE */
+                        /* preclude from marking dir complete */
+                        fi->dir_release_count--;
                 }
 
                 /* note next offset and last dentry name */
@@ -428,9 +429,9 @@ more:
          * the complete dir contents in our cache.
          */
         spin_lock(&ci->i_ceph_lock);
-        if (ci->i_release_count == fi->dir_release_count) {
+        if (atomic_read(&ci->i_release_count) == fi->dir_release_count) {
                 dout(" marking %p complete\n", inode);
-                ci->i_ceph_flags |= CEPH_I_COMPLETE;
+                __ceph_dir_set_complete(ci, fi->dir_release_count);
                 ci->i_max_offset = filp->f_pos;
         }
         spin_unlock(&ci->i_ceph_lock);
@@ -605,7 +606,7 @@ static struct dentry *ceph_lookup(struct inode *dir, struct dentry *dentry,
                             fsc->mount_options->snapdir_name,
                             dentry->d_name.len) &&
                     !is_root_ceph_dentry(dir, dentry) &&
-                    (ci->i_ceph_flags & CEPH_I_COMPLETE) &&
+                    __ceph_dir_is_complete(ci) &&
                     (__ceph_caps_issued_mask(ci, CEPH_CAP_FILE_SHARED, 1))) {
                         spin_unlock(&ci->i_ceph_lock);
                         dout(" dir %p complete, -ENOENT\n", dir);
@@ -909,7 +910,7 @@ static int ceph_rename(struct inode *old_dir, struct dentry *old_dentry,
                  */
 
                 /* d_move screws up d_subdirs order */
-                ceph_i_clear(new_dir, CEPH_I_COMPLETE);
+                ceph_dir_clear_complete(new_dir);
 
                 d_move(old_dentry, new_dentry);
 
@@ -1079,7 +1080,7 @@ static void ceph_d_prune(struct dentry *dentry)
         if (IS_ROOT(dentry))
                 return;
 
-        /* if we are not hashed, we don't affect I_COMPLETE */
+        /* if we are not hashed, we don't affect dir's completeness */
         if (d_unhashed(dentry))
                 return;
 
@@ -1087,7 +1088,7 @@ static void ceph_d_prune(struct dentry *dentry)
          * we hold d_lock, so d_parent is stable, and d_fsdata is never
          * cleared until d_release
          */
-        ceph_i_clear(dentry->d_parent->d_inode, CEPH_I_COMPLETE);
+        ceph_dir_clear_complete(dentry->d_parent->d_inode);
 }
 
 /*
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index eeac43dd04eb..1b173edc8083 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -302,7 +302,8 @@ struct inode *ceph_alloc_inode(struct super_block *sb)
         ci->i_version = 0;
         ci->i_time_warp_seq = 0;
         ci->i_ceph_flags = 0;
-        ci->i_release_count = 0;
+        atomic_set(&ci->i_release_count, 1);
+        atomic_set(&ci->i_complete_count, 0);
         ci->i_symlink = NULL;
 
         memset(&ci->i_dir_layout, 0, sizeof(ci->i_dir_layout));
@@ -721,9 +722,9 @@ static int fill_inode(struct inode *inode,
             ceph_snap(inode) == CEPH_NOSNAP &&
             (le32_to_cpu(info->cap.caps) & CEPH_CAP_FILE_SHARED) &&
             (issued & CEPH_CAP_FILE_EXCL) == 0 &&
-            (ci->i_ceph_flags & CEPH_I_COMPLETE) == 0) {
+            !__ceph_dir_is_complete(ci)) {
                 dout(" marking %p complete (empty)\n", inode);
-                ci->i_ceph_flags |= CEPH_I_COMPLETE;
+                __ceph_dir_set_complete(ci, atomic_read(&ci->i_release_count));
                 ci->i_max_offset = 2;
         }
 no_change:
@@ -857,7 +858,7 @@ static void ceph_set_dentry_offset(struct dentry *dn)
         di = ceph_dentry(dn);
 
         spin_lock(&ci->i_ceph_lock);
-        if ((ceph_inode(inode)->i_ceph_flags & CEPH_I_COMPLETE) == 0) {
+        if (!__ceph_dir_is_complete(ci)) {
                 spin_unlock(&ci->i_ceph_lock);
                 return;
         }
@@ -1061,8 +1062,8 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req,
                         /*
                          * d_move() puts the renamed dentry at the end of
                          * d_subdirs.  We need to assign it an appropriate
-                         * directory offset so we can behave when holding
-                         * I_COMPLETE.
+                         * directory offset so we can behave when dir is
+                         * complete.
                          */
                         ceph_set_dentry_offset(req->r_old_dentry);
                         dout("dn %p gets new offset %lld\n", req->r_old_dentry, 
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 600d770d70f7..0db6f5206d11 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -2034,20 +2034,16 @@ out:
 }
 
 /*
- * Invalidate dir I_COMPLETE, dentry lease state on an aborted MDS
+ * Invalidate dir's completeness, dentry lease state on an aborted MDS
  * namespace request.
  */
 void ceph_invalidate_dir_request(struct ceph_mds_request *req)
 {
         struct inode *inode = req->r_locked_dir;
-        struct ceph_inode_info *ci = ceph_inode(inode);
 
-        dout("invalidate_dir_request %p (I_COMPLETE, lease(s))\n", inode);
-        spin_lock(&ci->i_ceph_lock);
-        ci->i_ceph_flags &= ~CEPH_I_COMPLETE;
-        ci->i_release_count++;
-        spin_unlock(&ci->i_ceph_lock);
+        dout("invalidate_dir_request %p (complete, lease(s))\n", inode);
 
+        ceph_dir_clear_complete(inode);
         if (req->r_dentry)
                 ceph_invalidate_dentry_lease(req->r_dentry);
         if (req->r_old_dentry)
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index a04eda714df4..8696be2ff679 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -244,7 +244,8 @@ struct ceph_inode_info {
         u32 i_time_warp_seq;
 
         unsigned i_ceph_flags;
-        unsigned long i_release_count;
+        atomic_t i_release_count;
+        atomic_t i_complete_count;
 
         struct ceph_dir_layout i_dir_layout;
         struct ceph_file_layout i_layout;
@@ -254,7 +255,7 @@ struct ceph_inode_info {
         struct timespec i_rctime;
         u64 i_rbytes, i_rfiles, i_rsubdirs;
         u64 i_files, i_subdirs;
-        u64 i_max_offset;  /* largest readdir offset, set with I_COMPLETE */
+        u64 i_max_offset;  /* largest readdir offset, set with complete dir */
 
         struct rb_root i_fragtree;
         struct mutex i_fragtree_mutex;
@@ -419,38 +420,35 @@ static inline struct inode *ceph_find_inode(struct super_block *sb,
 /*
  * Ceph inode.
  */
-#define CEPH_I_COMPLETE  1  /* we have complete directory cached */
 #define CEPH_I_NODELAY   4  /* do not delay cap release */
 #define CEPH_I_FLUSH     8  /* do not delay flush of dirty metadata */
 #define CEPH_I_NOFLUSH  16  /* do not flush dirty caps */
 
-static inline void ceph_i_clear(struct inode *inode, unsigned mask)
+static inline void __ceph_dir_set_complete(struct ceph_inode_info *ci,
+                                           int release_count)
 {
-        struct ceph_inode_info *ci = ceph_inode(inode);
-
-        spin_lock(&ci->i_ceph_lock);
-        ci->i_ceph_flags &= ~mask;
-        spin_unlock(&ci->i_ceph_lock);
+        atomic_set(&ci->i_complete_count, release_count);
 }
 
-static inline void ceph_i_set(struct inode *inode, unsigned mask)
+static inline void __ceph_dir_clear_complete(struct ceph_inode_info *ci)
 {
-        struct ceph_inode_info *ci = ceph_inode(inode);
+        atomic_inc(&ci->i_release_count);
+}
 
-        spin_lock(&ci->i_ceph_lock);
-        ci->i_ceph_flags |= mask;
-        spin_unlock(&ci->i_ceph_lock);
+static inline bool __ceph_dir_is_complete(struct ceph_inode_info *ci)
+{
+        return atomic_read(&ci->i_complete_count) ==
+                atomic_read(&ci->i_release_count);
 }
 
-static inline bool ceph_i_test(struct inode *inode, unsigned mask)
+static inline void ceph_dir_clear_complete(struct inode *inode)
 {
-        struct ceph_inode_info *ci = ceph_inode(inode);
-        bool r;
+        __ceph_dir_clear_complete(ceph_inode(inode));
+}
 
-        spin_lock(&ci->i_ceph_lock);
-        r = (ci->i_ceph_flags & mask) == mask;
-        spin_unlock(&ci->i_ceph_lock);
-        return r;
+static inline bool ceph_dir_is_complete(struct inode *inode)
+{
+        return __ceph_dir_is_complete(ceph_inode(inode));
 }
 
 
@@ -565,7 +563,7 @@ struct ceph_file_info {
         u64 next_offset;       /* offset of next chunk (last_name's + 1) */
         char *last_name;       /* last entry in previous chunk */
         struct dentry *dentry; /* next dentry (for dcache readdir) */
-        unsigned long dir_release_count;
+        int dir_release_count;
 
         /* used for -o dirstat read() on directory thing */
         char *dir_info;