ext4: refactor truncate code

Move common code in ext4_ind_truncate() and ext4_ext_truncate() into
ext4_truncate().  This saves over 60 lines of code.

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

4 files changed, 78 insertions, 148 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 0649253804c4..d05ba3886f33 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2109,7 +2109,7 @@ extern ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb,
                                 unsigned long nr_segs);
 extern int ext4_ind_calc_metadata_amount(struct inode *inode, sector_t lblock);
 extern int ext4_ind_trans_blocks(struct inode *inode, int nrblocks, int chunk);
-extern void ext4_ind_truncate(struct inode *inode);
+extern void ext4_ind_truncate(handle_t *, struct inode *inode);
 extern int ext4_free_hole_blocks(handle_t *handle, struct inode *inode,
                                  ext4_lblk_t first, ext4_lblk_t stop);
 
@@ -2575,7 +2575,7 @@ extern int ext4_ext_index_trans_blocks(struct inode *inode, int nrblocks,
                                        int chunk);
 extern int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
                                struct ext4_map_blocks *map, int flags);
-extern void ext4_ext_truncate(struct inode *);
+extern void ext4_ext_truncate(handle_t *, struct inode *);
 extern int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start,
                                  ext4_lblk_t end);
 extern void ext4_ext_init(struct super_block *);
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index d58365e40df7..cbbe8a4deac6 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4257,48 +4257,13 @@ out3:
         return err ? err : allocated;
 }
 
-void ext4_ext_truncate(struct inode *inode)
+void ext4_ext_truncate(handle_t *handle, struct inode *inode)
 {
-        struct address_space *mapping = inode->i_mapping;
         struct super_block *sb = inode->i_sb;
         ext4_lblk_t last_block;
-        handle_t *handle;
-        loff_t page_len;
         int err = 0;
 
         /*
-         * finish any pending end_io work so we won't run the risk of
-         * converting any truncated blocks to initialized later
-         */
-        ext4_flush_unwritten_io(inode);
-
-        /*
-         * probably first extent we're gonna free will be last in block
-         */
-        err = ext4_writepage_trans_blocks(inode);
-        handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, err);
-        if (IS_ERR(handle))
-                return;
-
-        if (inode->i_size % PAGE_CACHE_SIZE != 0) {
-                page_len = PAGE_CACHE_SIZE -
-                        (inode->i_size & (PAGE_CACHE_SIZE - 1));
-
-                err = ext4_discard_partial_page_buffers(handle,
-                        mapping, inode->i_size, page_len, 0);
-
-                if (err)
-                        goto out_stop;
-        }
-
-        if (ext4_orphan_add(handle, inode))
-                goto out_stop;
-
-        down_write(&EXT4_I(inode)->i_data_sem);
-
-        ext4_discard_preallocations(inode);
-
-        /*
          * TODO: optimization is possible here.
          * Probably we need not scan at all,
          * because page truncation is enough.
@@ -4313,29 +4278,6 @@ void ext4_ext_truncate(struct inode *inode)
         err = ext4_es_remove_extent(inode, last_block,
                                     EXT_MAX_BLOCKS - last_block);
         err = ext4_ext_remove_space(inode, last_block, EXT_MAX_BLOCKS - 1);
-
-        /* In a multi-transaction truncate, we only make the final
-         * transaction synchronous.
-         */
-        if (IS_SYNC(inode))
-                ext4_handle_sync(handle);
-
-        up_write(&EXT4_I(inode)->i_data_sem);
-
-out_stop:
-        /*
-         * If this was a simple ftruncate() and the file will remain alive,
-         * then we need to clear up the orphan record which we created above.
-         * However, if this was a real unlink then we were called by
-         * ext4_delete_inode(), and we allow that function to clean up the
-         * orphan info for us.
-         */
-        if (inode->i_nlink)
-                ext4_orphan_del(handle, inode);
-
-        inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
-        ext4_mark_inode_dirty(handle, inode);
-        ext4_journal_stop(handle);
 }
 
 static void ext4_falloc_update_inode(struct inode *inode,
diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
index d8846779f4ea..98be6f697463 100644
--- a/fs/ext4/indirect.c
+++ b/fs/ext4/indirect.c
@@ -806,26 +806,9 @@ int ext4_ind_trans_blocks(struct inode *inode, int nrblocks, int chunk)
  * be able to restart the transaction at a conventient checkpoint to make
  * sure we don't overflow the journal.
  *
- * start_transaction gets us a new handle for a truncate transaction,
- * and extend_transaction tries to extend the existing one a bit.  If
+ * Try to extend this transaction for the purposes of truncation.  If
  * extend fails, we need to propagate the failure up and restart the
  * transaction in the top-level truncate loop. --sct
- */
-static handle_t *start_transaction(struct inode *inode)
-{
-        handle_t *result;
-
-        result = ext4_journal_start(inode, EXT4_HT_TRUNCATE,
-                                    ext4_blocks_for_truncate(inode));
-        if (!IS_ERR(result))
-                return result;
-
-        ext4_std_error(inode->i_sb, PTR_ERR(result));
-        return result;
-}
-
-/*
- * Try to extend this transaction for the purposes of truncation.
  *
  * Returns 0 if we managed to create more room.  If we can't create more
  * room, and the transaction must be restarted we return 1.
@@ -1218,68 +1201,30 @@ static void ext4_free_branches(handle_t *handle, struct inode *inode,
         }
 }
 
-void ext4_ind_truncate(struct inode *inode)
+void ext4_ind_truncate(handle_t *handle, struct inode *inode)
 {
-        handle_t *handle;
         struct ext4_inode_info *ei = EXT4_I(inode);
         __le32 *i_data = ei->i_data;
         int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
-        struct address_space *mapping = inode->i_mapping;
         ext4_lblk_t offsets[4];
         Indirect chain[4];
         Indirect *partial;
         __le32 nr = 0;
         int n = 0;
         ext4_lblk_t last_block, max_block;
-        loff_t page_len;
         unsigned blocksize = inode->i_sb->s_blocksize;
-        int err;
-
-        handle = start_transaction(inode);
-        if (IS_ERR(handle))
-                return;         /* AKPM: return what? */
 
         last_block = (inode->i_size + blocksize-1)
                                         >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
         max_block = (EXT4_SB(inode->i_sb)->s_bitmap_maxbytes + blocksize-1)
                                         >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
 
-        if (inode->i_size % PAGE_CACHE_SIZE != 0) {
-                page_len = PAGE_CACHE_SIZE -
-                        (inode->i_size & (PAGE_CACHE_SIZE - 1));
-
-                err = ext4_discard_partial_page_buffers(handle,
-                        mapping, inode->i_size, page_len, 0);
-
-                if (err)
-                        goto out_stop;
-        }
-
         if (last_block != max_block) {
                 n = ext4_block_to_path(inode, last_block, offsets, NULL);
                 if (n == 0)
-                        goto out_stop;  /* error */
+                        return;
         }
 
-        /*
-         * OK.  This truncate is going to happen.  We add the inode to the
-         * orphan list, so that if this truncate spans multiple transactions,
-         * and we crash, we will resume the truncate when the filesystem
-         * recovers.  It also marks the inode dirty, to catch the new size.
-         *
-         * Implication: the file must always be in a sane, consistent
-         * truncatable state while each transaction commits.
-         */
-        if (ext4_orphan_add(handle, inode))
-                goto out_stop;
-
-        /*
-         * From here we block out all ext4_get_block() callers who want to
-         * modify the block allocation tree.
-         */
-        down_write(&ei->i_data_sem);
-
-        ext4_discard_preallocations(inode);
         ext4_es_remove_extent(inode, last_block, EXT_MAX_BLOCKS - last_block);
 
         /*
@@ -1296,7 +1241,7 @@ void ext4_ind_truncate(struct inode *inode)
                  * It is unnecessary to free any data blocks if last_block is
                  * equal to the indirect block limit.
                  */
-                goto out_unlock;
+                return;
         } else if (n == 1) {            /* direct blocks */
                 ext4_free_data(handle, inode, NULL, i_data+offsets[0],
                                i_data + EXT4_NDIR_BLOCKS);
@@ -1356,31 +1301,6 @@ do_indirects:
         case EXT4_TIND_BLOCK:
                 ;
         }
-
-out_unlock:
-        up_write(&ei->i_data_sem);
-        inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
-        ext4_mark_inode_dirty(handle, inode);
-
-        /*
-         * In a multi-transaction truncate, we only make the final transaction
-         * synchronous
-         */
-        if (IS_SYNC(inode))
-                ext4_handle_sync(handle);
-out_stop:
-        /*
-         * If this was a simple ftruncate(), and the file will remain alive
-         * then we need to clear up the orphan record which we created above.
-         * However, if this was a real unlink then we were called by
-         * ext4_delete_inode(), and we allow that function to clean up the
-         * orphan info for us.
-         */
-        if (inode->i_nlink)
-                ext4_orphan_del(handle, inode);
-
-        ext4_journal_stop(handle);
-        trace_ext4_truncate_exit(inode);
 }
 
 static int free_hole_blocks(handle_t *handle, struct inode *inode,
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 9bda50aa34e2..49c80e4ac5ac 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3738,9 +3738,9 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
                                             stop_block);
 
         ext4_discard_preallocations(inode);
+        up_write(&EXT4_I(inode)->i_data_sem);
         if (IS_SYNC(inode))
                 ext4_handle_sync(handle);
-        up_write(&EXT4_I(inode)->i_data_sem);
         inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
         ext4_mark_inode_dirty(handle, inode);
 out_stop:
@@ -3782,6 +3782,12 @@ out_mutex:
  */
 void ext4_truncate(struct inode *inode)
 {
+        struct ext4_inode_info *ei = EXT4_I(inode);
+        unsigned int credits;
+        handle_t *handle;
+        struct address_space *mapping = inode->i_mapping;
+        loff_t page_len;
+
         trace_ext4_truncate_enter(inode);
 
         if (!ext4_can_truncate(inode))
@@ -3800,10 +3806,72 @@ void ext4_truncate(struct inode *inode)
                         return;
         }
 
+        /*
+         * finish any pending end_io work so we won't run the risk of
+         * converting any truncated blocks to initialized later
+         */
+        ext4_flush_unwritten_io(inode);
+
+        if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
+                credits = ext4_writepage_trans_blocks(inode);
+        else
+                credits = ext4_blocks_for_truncate(inode);
+
+        handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, credits);
+        if (IS_ERR(handle)) {
+                ext4_std_error(inode->i_sb, PTR_ERR(handle));
+                return;
+        }
+
+        if (inode->i_size % PAGE_CACHE_SIZE != 0) {
+                page_len = PAGE_CACHE_SIZE -
+                        (inode->i_size & (PAGE_CACHE_SIZE - 1));
+
+                if (ext4_discard_partial_page_buffers(handle,
+                                mapping, inode->i_size, page_len, 0))
+                        goto out_stop;
+        }
+
+        /*
+         * We add the inode to the orphan list, so that if this
+         * truncate spans multiple transactions, and we crash, we will
+         * resume the truncate when the filesystem recovers.  It also
+         * marks the inode dirty, to catch the new size.
+         *
+         * Implication: the file must always be in a sane, consistent
+         * truncatable state while each transaction commits.
+         */
+        if (ext4_orphan_add(handle, inode))
+                goto out_stop;
+
+        down_write(&EXT4_I(inode)->i_data_sem);
+
+        ext4_discard_preallocations(inode);
+
         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
-                ext4_ext_truncate(inode);
+                ext4_ext_truncate(handle, inode);
         else
-                ext4_ind_truncate(inode);
+                ext4_ind_truncate(handle, inode);
+
+        up_write(&ei->i_data_sem);
+
+        if (IS_SYNC(inode))
+                ext4_handle_sync(handle);
+
+out_stop:
+        /*
+         * If this was a simple ftruncate() and the file will remain alive,
+         * then we need to clear up the orphan record which we created above.
+         * However, if this was a real unlink then we were called by
+         * ext4_delete_inode(), and we allow that function to clean up the
+         * orphan info for us.
+         */
+        if (inode->i_nlink)
+                ext4_orphan_del(handle, inode);
+
+        inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
+        ext4_mark_inode_dirty(handle, inode);
+        ext4_journal_stop(handle);
 
         trace_ext4_truncate_exit(inode);
 }