Commit 819c4920 authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

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: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 26a4c0c6

fs/ext4/ext4.h

+2 −2
Original line number Diff line number Diff line
@@ -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 *);

fs/ext4/extents.c

+1 −59
Original line number Diff line number Diff line
@@ -4257,47 +4257,12 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode, 
	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,
@@ -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,

fs/ext4/indirect.c

+4 −84
Original line number Diff line number Diff line
@@ -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 @@ void ext4_ind_truncate(struct inode *inode) 
	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,

fs/ext4/inode.c

+71 −3
Original line number Diff line number Diff line
@@ -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 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length) 
 */

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);

}