ext4: fix sparse warnings

Add sparse annotations to suppress false positive context imbalance
warnings, and use NULL instead of 0 in EXT_MAX_{EXTENT,INDEX}.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/ext4_extents.h b/fs/ext4/ext4_extents.h
index 44e5988..26435f3 100644 (file)
--- a/fs/ext4/ext4_extents.h
+++ b/fs/ext4/ext4_extents.h
@@ -173,10 +173,11 @@ struct partial_cluster {
 #define EXT_MAX_EXTENT(__hdr__)        \
        ((le16_to_cpu((__hdr__)->eh_max)) ? \
        ((EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)) \
-                                       : 0)
+                                       : NULL)
 #define EXT_MAX_INDEX(__hdr__) \
        ((le16_to_cpu((__hdr__)->eh_max)) ? \
-       ((EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)) : 0)
+       ((EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)) \
+                                       : NULL)
 
 static inline struct ext4_extent_header *ext_inode_hdr(struct inode *inode)
 {

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 34670cb..665646a 100644 (file)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2478,6 +2478,12 @@ static bool ext4_mb_good_group(struct ext4_allocation_context *ac,
  * This could return negative error code if something goes wrong
  * during ext4_mb_init_group(). This should not be called with
  * ext4_lock_group() held.
+ *
+ * Note: because we are conditionally operating with the group lock in
+ * the EXT4_MB_STRICT_CHECK case, we need to fake out sparse in this
+ * function using __acquire and __release.  This means we need to be
+ * super careful before messing with the error path handling via "goto
+ * out"!
  */
 static int ext4_mb_good_group_nolock(struct ext4_allocation_context *ac,
                                     ext4_group_t group, int cr)
@@ -2491,8 +2497,10 @@ static int ext4_mb_good_group_nolock(struct ext4_allocation_context *ac,
 
        if (sbi->s_mb_stats)
                atomic64_inc(&sbi->s_bal_cX_groups_considered[ac->ac_criteria]);
-       if (should_lock)
+       if (should_lock) {
                ext4_lock_group(sb, group);
+               __release(ext4_group_lock_ptr(sb, group));
+       }
        free = grp->bb_free;
        if (free == 0)
                goto out;
@@ -2500,8 +2508,10 @@ static int ext4_mb_good_group_nolock(struct ext4_allocation_context *ac,
                goto out;
        if (unlikely(EXT4_MB_GRP_BBITMAP_CORRUPT(grp)))
                goto out;
-       if (should_lock)
+       if (should_lock) {
+               __acquire(ext4_group_lock_ptr(sb, group));
                ext4_unlock_group(sb, group);
+       }
 
        /* We only do this if the grp has never been initialized */
        if (unlikely(EXT4_MB_GRP_NEED_INIT(grp))) {
@@ -2528,12 +2538,16 @@ static int ext4_mb_good_group_nolock(struct ext4_allocation_context *ac,
                        return ret;
        }
 
-       if (should_lock)
+       if (should_lock) {
                ext4_lock_group(sb, group);
+               __release(ext4_group_lock_ptr(sb, group));
+       }
        ret = ext4_mb_good_group(ac, group, cr);
 out:
-       if (should_lock)
+       if (should_lock) {
+               __acquire(ext4_group_lock_ptr(sb, group));
                ext4_unlock_group(sb, group);
+       }
        return ret;
 }
 
@@ -2969,6 +2983,7 @@ int ext4_seq_mb_stats_show(struct seq_file *seq, void *offset)
 }
 
 static void *ext4_mb_seq_structs_summary_start(struct seq_file *seq, loff_t *pos)
+__acquires(&EXT4_SB(sb)->s_mb_rb_lock)
 {
        struct super_block *sb = PDE_DATA(file_inode(seq->file));
        unsigned long position;
@@ -3041,6 +3056,7 @@ static int ext4_mb_seq_structs_summary_show(struct seq_file *seq, void *v)
 }
 
 static void ext4_mb_seq_structs_summary_stop(struct seq_file *seq, void *v)
+__releases(&EXT4_SB(sb)->s_mb_rb_lock)
 {
        struct super_block *sb = PDE_DATA(file_inode(seq->file));
 
@@ -6275,6 +6291,8 @@ __acquires(bitlock)
 static int ext4_try_to_trim_range(struct super_block *sb,
                struct ext4_buddy *e4b, ext4_grpblk_t start,
                ext4_grpblk_t max, ext4_grpblk_t minblocks)
+__acquires(ext4_group_lock_ptr(sb, e4b->bd_group))
+__releases(ext4_group_lock_ptr(sb, e4b->bd_group))
 {
        ext4_grpblk_t next, count, free_count;
        void *bitmap;