ceph: introduce a new inode flag indicating if cached dentries are ordered

After creating/deleting/renaming file, offsets of sibling dentries may
change. So we can not use cached dentries to satisfy readdir. But we can
still use the cached dentries to conclude -ENOENT for lookup.

This patch introduces a new inode flag indicating if child dentries are
ordered. The flag is set at the same time marking a directory complete.
After creating/deleting/renaming file, we clear the flag on directory
inode. This prevents ceph_readdir() from using cached dentries to satisfy
readdir syscall.

Signed-off-by: Yan, Zheng <zyan@redhat.com>

3 files changed, 55 insertions, 19 deletions

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index e6d63f8f98c0..652619950fa9 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -183,7 +183,7 @@ more:
         spin_unlock(&parent->d_lock);
 
         /* make sure a dentry wasn't dropped while we didn't have parent lock */
-        if (!ceph_dir_is_complete(dir)) {
+        if (!ceph_dir_is_complete_ordered(dir)) {
                 dout(" lost dir complete on %p; falling back to mds\n", dir);
                 dput(dentry);
                 err = -EAGAIN;
@@ -261,10 +261,6 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
 
         /* always start with . and .. */
         if (ctx->pos == 0) {
-                /* note dir version at start of readdir so we can tell
-                 * if any dentries get dropped */
-                fi->dir_release_count = atomic_read(&ci->i_release_count);
-
                 dout("readdir off 0 -> '.'\n");
                 if (!dir_emit(ctx, ".", 1, 
                             ceph_translate_ino(inode->i_sb, inode->i_ino),
@@ -289,7 +285,7 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
         if ((ctx->pos == 2 || fi->dentry) &&
             !ceph_test_mount_opt(fsc, NOASYNCREADDIR) &&
             ceph_snap(inode) != CEPH_SNAPDIR &&
-            __ceph_dir_is_complete(ci) &&
+            __ceph_dir_is_complete_ordered(ci) &&
             __ceph_caps_issued_mask(ci, CEPH_CAP_FILE_SHARED, 1)) {
                 u32 shared_gen = ci->i_shared_gen;
                 spin_unlock(&ci->i_ceph_lock);
@@ -312,6 +308,13 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
 
         /* proceed with a normal readdir */
 
+        if (ctx->pos == 2) {
+                /* note dir version at start of readdir so we can tell
+                 * if any dentries get dropped */
+                fi->dir_release_count = atomic_read(&ci->i_release_count);
+                fi->dir_ordered_count = ci->i_ordered_count;
+        }
+
 more:
         /* do we have the correct frag content buffered? */
         if (fi->frag != frag || fi->last_readdir == NULL) {
@@ -446,8 +449,12 @@ more:
          */
         spin_lock(&ci->i_ceph_lock);
         if (atomic_read(&ci->i_release_count) == fi->dir_release_count) {
-                dout(" marking %p complete\n", inode);
-                __ceph_dir_set_complete(ci, fi->dir_release_count);
+                if (ci->i_ordered_count == fi->dir_ordered_count)
+                        dout(" marking %p complete and ordered\n", inode);
+                else
+                        dout(" marking %p complete\n", inode);
+                __ceph_dir_set_complete(ci, fi->dir_release_count,
+                                        fi->dir_ordered_count);
         }
         spin_unlock(&ci->i_ceph_lock);
 
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 7b6139004401..72607c17e6fd 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -389,6 +389,7 @@ 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_ordered_count = 0;
         atomic_set(&ci->i_release_count, 1);
         atomic_set(&ci->i_complete_count, 0);
         ci->i_symlink = NULL;
@@ -845,7 +846,8 @@ static int fill_inode(struct inode *inode,
             (issued & CEPH_CAP_FILE_EXCL) == 0 &&
             !__ceph_dir_is_complete(ci)) {
                 dout(" marking %p complete (empty)\n", inode);
-                __ceph_dir_set_complete(ci, atomic_read(&ci->i_release_count));
+                __ceph_dir_set_complete(ci, atomic_read(&ci->i_release_count),
+                                        ci->i_ordered_count);
         }
 
         /* were we issued a capability? */
@@ -1206,8 +1208,8 @@ retry_lookup:
                         ceph_invalidate_dentry_lease(dn);
 
                         /* d_move screws up sibling dentries' offsets */
-                        ceph_dir_clear_complete(dir);
-                        ceph_dir_clear_complete(olddir);
+                        ceph_dir_clear_ordered(dir);
+                        ceph_dir_clear_ordered(olddir);
 
                         dout("dn %p gets new offset %lld\n", req->r_old_dentry,
                              ceph_dentry(req->r_old_dentry)->offset);
@@ -1219,6 +1221,7 @@ retry_lookup:
                 if (!rinfo->head->is_target) {
                         dout("fill_trace null dentry\n");
                         if (dn->d_inode) {
+                                ceph_dir_clear_ordered(dir);
                                 dout("d_delete %p\n", dn);
                                 d_delete(dn);
                         } else {
@@ -1235,7 +1238,7 @@ retry_lookup:
 
                 /* attach proper inode */
                 if (!dn->d_inode) {
-                        ceph_dir_clear_complete(dir);
+                        ceph_dir_clear_ordered(dir);
                         ihold(in);
                         dn = splice_dentry(dn, in, &have_lease);
                         if (IS_ERR(dn)) {
@@ -1265,7 +1268,7 @@ retry_lookup:
                 BUG_ON(!dir);
                 BUG_ON(ceph_snap(dir) != CEPH_SNAPDIR);
                 dout(" linking snapped dir %p to dn %p\n", in, dn);
-                ceph_dir_clear_complete(dir);
+                ceph_dir_clear_ordered(dir);
                 ihold(in);
                 dn = splice_dentry(dn, in, NULL);
                 if (IS_ERR(dn)) {
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index b82f507979b8..aca22879b41f 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -256,6 +256,7 @@ struct ceph_inode_info {
         u32 i_time_warp_seq;
 
         unsigned i_ceph_flags;
+        int i_ordered_count;
         atomic_t i_release_count;
         atomic_t i_complete_count;
 
@@ -434,14 +435,19 @@ static inline struct inode *ceph_find_inode(struct super_block *sb,
 /*
  * Ceph inode.
  */
-#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 */
+#define CEPH_I_DIR_ORDERED      1  /* dentries in dir are ordered */
+#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_dir_set_complete(struct ceph_inode_info *ci,
-                                           int release_count)
+                                           int release_count, int ordered_count)
 {
         atomic_set(&ci->i_complete_count, release_count);
+        if (ci->i_ordered_count == ordered_count)
+                ci->i_ceph_flags |= CEPH_I_DIR_ORDERED;
+        else
+                ci->i_ceph_flags &= ~CEPH_I_DIR_ORDERED;
 }
 
 static inline void __ceph_dir_clear_complete(struct ceph_inode_info *ci)
@@ -455,16 +461,35 @@ static inline bool __ceph_dir_is_complete(struct ceph_inode_info *ci)
                 atomic_read(&ci->i_release_count);
 }
 
+static inline bool __ceph_dir_is_complete_ordered(struct ceph_inode_info *ci)
+{
+        return __ceph_dir_is_complete(ci) &&
+                (ci->i_ceph_flags & CEPH_I_DIR_ORDERED);
+}
+
 static inline void ceph_dir_clear_complete(struct inode *inode)
 {
         __ceph_dir_clear_complete(ceph_inode(inode));
 }
 
-static inline bool ceph_dir_is_complete(struct inode *inode)
+static inline void ceph_dir_clear_ordered(struct inode *inode)
 {
-        return __ceph_dir_is_complete(ceph_inode(inode));
+        struct ceph_inode_info *ci = ceph_inode(inode);
+        spin_lock(&ci->i_ceph_lock);
+        ci->i_ordered_count++;
+        ci->i_ceph_flags &= ~CEPH_I_DIR_ORDERED;
+        spin_unlock(&ci->i_ceph_lock);
 }
 
+static inline bool ceph_dir_is_complete_ordered(struct inode *inode)
+{
+        struct ceph_inode_info *ci = ceph_inode(inode);
+        bool ret;
+        spin_lock(&ci->i_ceph_lock);
+        ret = __ceph_dir_is_complete_ordered(ci);
+        spin_unlock(&ci->i_ceph_lock);
+        return ret;
+}
 
 /* find a specific frag @f */
 extern struct ceph_inode_frag *__ceph_find_frag(struct ceph_inode_info *ci,
@@ -580,6 +605,7 @@ struct ceph_file_info {
         char *last_name;       /* last entry in previous chunk */
         struct dentry *dentry; /* next dentry (for dcache readdir) */
         int dir_release_count;
+        int dir_ordered_count;
 
         /* used for -o dirstat read() on directory thing */
         char *dir_info;