ext4: Replace BUG_ON() with ext4_error() in move_extents.c

Replace BUG_ON calls with a call to ext4_error()
to print an error message if EXT4_IOC_MOVE_EXT failed
with some kind of reasons.  This will help to debug.
Ted pointed this out, thanks.

Signed-off-by: Akira Fujita <a-fujita@rs.jp.nec.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 109 insertions, 40 deletions

diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index e4bd8761498a..2258560e9722 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -128,6 +128,31 @@ mext_next_extent(struct inode *inode, struct ext4_ext_path *path,
 }
 
 /**
+ * mext_check_null_inode - NULL check for two inodes
+ *
+ * If inode1 or inode2 is NULL, return -EIO. Otherwise, return 0.
+ */
+static int
+mext_check_null_inode(struct inode *inode1, struct inode *inode2,
+                const char *function)
+{
+        int ret = 0;
+
+        if (inode1 == NULL) {
+                ext4_error(inode2->i_sb, function,
+                        "Both inodes should not be NULL: "
+                        "inode1 NULL inode2 %lu", inode2->i_ino);
+                ret = -EIO;
+        } else if (inode2 == NULL) {
+                ext4_error(inode1->i_sb, function,
+                        "Both inodes should not be NULL: "
+                        "inode1 %lu inode2 NULL", inode1->i_ino);
+                ret = -EIO;
+        }
+        return ret;
+}
+
+/**
  * mext_double_down_read - Acquire two inodes' read semaphore
  *
  * @orig_inode:         original inode structure
@@ -139,8 +164,6 @@ mext_double_down_read(struct inode *orig_inode, struct inode *donor_inode)
 {
         struct inode *first = orig_inode, *second = donor_inode;
 
-        BUG_ON(orig_inode == NULL || donor_inode == NULL);
-
         /*
          * Use the inode number to provide the stable locking order instead
          * of its address, because the C language doesn't guarantee you can
@@ -167,8 +190,6 @@ mext_double_down_write(struct inode *orig_inode, struct inode *donor_inode)
 {
         struct inode *first = orig_inode, *second = donor_inode;
 
-        BUG_ON(orig_inode == NULL || donor_inode == NULL);
-
         /*
          * Use the inode number to provide the stable locking order instead
          * of its address, because the C language doesn't guarantee you can
@@ -193,8 +214,6 @@ mext_double_down_write(struct inode *orig_inode, struct inode *donor_inode)
 static void
 mext_double_up_read(struct inode *orig_inode, struct inode *donor_inode)
 {
-        BUG_ON(orig_inode == NULL || donor_inode == NULL);
-
         up_read(&EXT4_I(orig_inode)->i_data_sem);
         up_read(&EXT4_I(donor_inode)->i_data_sem);
 }
@@ -209,8 +228,6 @@ mext_double_up_read(struct inode *orig_inode, struct inode *donor_inode)
 static void
 mext_double_up_write(struct inode *orig_inode, struct inode *donor_inode)
 {
-        BUG_ON(orig_inode == NULL || donor_inode == NULL);
-
         up_write(&EXT4_I(orig_inode)->i_data_sem);
         up_write(&EXT4_I(donor_inode)->i_data_sem);
 }
@@ -534,7 +551,15 @@ mext_leaf_block(handle_t *handle, struct inode *orig_inode,
          * oext      |-----------|
          * new_ext       |-------|
          */
-        BUG_ON(le32_to_cpu(oext->ee_block) + oext_alen - 1 < new_ext_end);
+        if (le32_to_cpu(oext->ee_block) + oext_alen - 1 < new_ext_end) {
+                ext4_error(orig_inode->i_sb, __func__,
+                        "new_ext_end(%u) should be less than or equal to "
+                        "oext->ee_block(%u) + oext_alen(%d) - 1",
+                        new_ext_end, le32_to_cpu(oext->ee_block),
+                        oext_alen);
+                ret = -EIO;
+                goto out;
+        }
 
         /*
          * Case: new_ext is smaller than original extent
@@ -558,6 +583,7 @@ mext_leaf_block(handle_t *handle, struct inode *orig_inode,
 
         ret = mext_insert_extents(handle, orig_inode, orig_path, o_start,
                                 o_end, &start_ext, &new_ext, &end_ext);
+out:
         return ret;
 }
 
@@ -668,7 +694,20 @@ mext_replace_branches(handle_t *handle, struct inode *orig_inode,
         /* Loop for the donor extents */
         while (1) {
                 /* The extent for donor must be found. */
-                BUG_ON(!dext || donor_off != le32_to_cpu(tmp_dext.ee_block));
+                if (!dext) {
+                        ext4_error(donor_inode->i_sb, __func__,
+                                   "The extent for donor must be found");
+                        err = -EIO;
+                        goto out;
+                } else if (donor_off != le32_to_cpu(tmp_dext.ee_block)) {
+                        ext4_error(donor_inode->i_sb, __func__,
+                                "Donor offset(%u) and the first block of donor "
+                                "extent(%u) should be equal",
+                                donor_off,
+                                le32_to_cpu(tmp_dext.ee_block));
+                        err = -EIO;
+                        goto out;
+                }
 
                 /* Set donor extent to orig extent */
                 err = mext_leaf_block(handle, orig_inode,
@@ -1050,18 +1089,23 @@ mext_check_arguments(struct inode *orig_inode,
  * @inode1:     the inode structure
  * @inode2:     the inode structure
  *
- * Lock two inodes' i_mutex by i_ino order. This function is moved from
- * fs/inode.c.
+ * Lock two inodes' i_mutex by i_ino order.
+ * If inode1 or inode2 is NULL, return -EIO. Otherwise, return 0.
  */
-static void
+static int
 mext_inode_double_lock(struct inode *inode1, struct inode *inode2)
 {
-        if (inode1 == NULL || inode2 == NULL || inode1 == inode2) {
-                if (inode1)
-                        mutex_lock(&inode1->i_mutex);
-                else if (inode2)
-                        mutex_lock(&inode2->i_mutex);
-                return;
+        int ret = 0;
+
+        BUG_ON(inode1 == NULL && inode2 == NULL);
+
+        ret = mext_check_null_inode(inode1, inode2, __func__);
+        if (ret < 0)
+                goto out;
+
+        if (inode1 == inode2) {
+                mutex_lock(&inode1->i_mutex);
+                goto out;
         }
 
         if (inode1->i_ino < inode2->i_ino) {
@@ -1071,6 +1115,9 @@ mext_inode_double_lock(struct inode *inode1, struct inode *inode2)
                 mutex_lock_nested(&inode2->i_mutex, I_MUTEX_PARENT);
                 mutex_lock_nested(&inode1->i_mutex, I_MUTEX_CHILD);
         }
+
+out:
+        return ret;
 }
 
 /**
@@ -1079,17 +1126,28 @@ mext_inode_double_lock(struct inode *inode1, struct inode *inode2)
  * @inode1:     the inode that is released first
  * @inode2:     the inode that is released second
  *
- * This function is moved from fs/inode.c.
+ * If inode1 or inode2 is NULL, return -EIO. Otherwise, return 0.
  */
 
-static void
+static int
 mext_inode_double_unlock(struct inode *inode1, struct inode *inode2)
 {
+        int ret = 0;
+
+        BUG_ON(inode1 == NULL && inode2 == NULL);
+
+        ret = mext_check_null_inode(inode1, inode2, __func__);
+        if (ret < 0)
+                goto out;
+
         if (inode1)
                 mutex_unlock(&inode1->i_mutex);
 
         if (inode2 && inode2 != inode1)
                 mutex_unlock(&inode2->i_mutex);
+
+out:
+        return ret;
 }
 
 /**
@@ -1146,21 +1204,23 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp,
         ext4_lblk_t block_end, seq_start, add_blocks, file_end, seq_blocks = 0;
         ext4_lblk_t rest_blocks;
         pgoff_t orig_page_offset = 0, seq_end_page;
-        int ret, depth, last_extent = 0;
+        int ret1, ret2, depth, last_extent = 0;
         int blocks_per_page = PAGE_CACHE_SIZE >> orig_inode->i_blkbits;
         int data_offset_in_page;
         int block_len_in_page;
         int uninit;
 
         /* protect orig and donor against a truncate */
-        mext_inode_double_lock(orig_inode, donor_inode);
+        ret1 = mext_inode_double_lock(orig_inode, donor_inode);
+        if (ret1 < 0)
+                return ret1;
 
         mext_double_down_read(orig_inode, donor_inode);
         /* Check the filesystem environment whether move_extent can be done */
-        ret = mext_check_arguments(orig_inode, donor_inode, orig_start,
+        ret1 = mext_check_arguments(orig_inode, donor_inode, orig_start,
                                         donor_start, &len, *moved_len);
         mext_double_up_read(orig_inode, donor_inode);
-        if (ret)
+        if (ret1)
                 goto out2;
 
         file_end = (i_size_read(orig_inode) - 1) >> orig_inode->i_blkbits;
@@ -1168,19 +1228,19 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp,
         if (file_end < block_end)
                 len -= block_end - file_end;
 
-        ret = get_ext_path(orig_inode, block_start, &orig_path);
+        ret1 = get_ext_path(orig_inode, block_start, &orig_path);
         if (orig_path == NULL)
                 goto out2;
 
         /* Get path structure to check the hole */
-        ret = get_ext_path(orig_inode, block_start, &holecheck_path);
+        ret1 = get_ext_path(orig_inode, block_start, &holecheck_path);
         if (holecheck_path == NULL)
                 goto out;
 
         depth = ext_depth(orig_inode);
         ext_cur = holecheck_path[depth].p_ext;
         if (ext_cur == NULL) {
-                ret = -EINVAL;
+                ret1 = -EINVAL;
                 goto out;
         }
 
@@ -1193,13 +1253,13 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp,
                 last_extent = mext_next_extent(orig_inode,
                                         holecheck_path, &ext_cur);
                 if (last_extent < 0) {
-                        ret = last_extent;
+                        ret1 = last_extent;
                         goto out;
                 }
                 last_extent = mext_next_extent(orig_inode, orig_path,
                                                         &ext_dummy);
                 if (last_extent < 0) {
-                        ret = last_extent;
+                        ret1 = last_extent;
                         goto out;
                 }
         }
@@ -1209,7 +1269,7 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp,
         if (le32_to_cpu(ext_cur->ee_block) > block_end) {
                 ext4_debug("ext4 move extent: The specified range of file "
                                                         "may be the hole\n");
-                ret = -EINVAL;
+                ret1 = -EINVAL;
                 goto out;
         }
 
@@ -1229,7 +1289,7 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp,
                 last_extent = mext_next_extent(orig_inode, holecheck_path,
                                                 &ext_cur);
                 if (last_extent < 0) {
-                        ret = last_extent;
+                        ret1 = last_extent;
                         break;
                 }
                 add_blocks = ext4_ext_get_actual_len(ext_cur);
@@ -1281,16 +1341,23 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp,
                 while (orig_page_offset <= seq_end_page) {
 
                         /* Swap original branches with new branches */
-                        ret = move_extent_per_page(o_filp, donor_inode,
+                        ret1 = move_extent_per_page(o_filp, donor_inode,
                                                 orig_page_offset,
                                                 data_offset_in_page,
                                                 block_len_in_page, uninit);
-                        if (ret < 0)
+                        if (ret1 < 0)
                                 goto out;
                         orig_page_offset++;
                         /* Count how many blocks we have exchanged */
                         *moved_len += block_len_in_page;
-                        BUG_ON(*moved_len > len);
+                        if (*moved_len > len) {
+                                ext4_error(orig_inode->i_sb, __func__,
+                                        "We replaced blocks too much! "
+                                        "sum of replaced: %llu requested: %llu",
+                                        *moved_len, len);
+                                ret1 = -EIO;
+                                goto out;
+                        }
 
                         data_offset_in_page = 0;
                         rest_blocks -= block_len_in_page;
@@ -1303,7 +1370,7 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp,
                 /* Decrease buffer counter */
                 if (holecheck_path)
                         ext4_ext_drop_refs(holecheck_path);
-                ret = get_ext_path(orig_inode, seq_start, &holecheck_path);
+                ret1 = get_ext_path(orig_inode, seq_start, &holecheck_path);
                 if (holecheck_path == NULL)
                         break;
                 depth = holecheck_path->p_depth;
@@ -1311,7 +1378,7 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp,
                 /* Decrease buffer counter */
                 if (orig_path)
                         ext4_ext_drop_refs(orig_path);
-                ret = get_ext_path(orig_inode, seq_start, &orig_path);
+                ret1 = get_ext_path(orig_inode, seq_start, &orig_path);
                 if (orig_path == NULL)
                         break;
 
@@ -1330,10 +1397,12 @@ out:
                 kfree(holecheck_path);
         }
 out2:
-        mext_inode_double_unlock(orig_inode, donor_inode);
+        ret2 = mext_inode_double_unlock(orig_inode, donor_inode);
 
-        if (ret)
-                return ret;
+        if (ret1)
+                return ret1;
+        else if (ret2)
+                return ret2;
 
         return 0;
 }