Commit 6b523df4 authored by Jan Kara's avatar Jan Kara Committed by Theodore Ts'o
Browse files

ext4: use transaction reservation for extent conversion in ext4_end_io 



Later we would like to clear PageWriteback bit only after extent
conversion from unwritten to written extents is performed.  However it
is not possible to start a transaction after PageWriteback is set
because that violates lock ordering (and is easy to deadlock).  So we
have to reserve a transaction before locking pages and sending them
for IO and later we use the transaction for extent conversion from
ext4_end_io().

Reviewed-by: default avatarZheng Liu <wenqing.lz@taobao.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 3613d228

fs/ext4/ext4.h

+9 −3
Original line number Diff line number Diff line
@@ -184,10 +184,13 @@ struct ext4_map_blocks { 
#define EXT4_IO_END_DIRECT	0x0004



/*

 * For converting uninitialized extents on a work queue.

 * For converting uninitialized extents on a work queue. 'handle' is used for

 * buffered writeback.

 */

typedef struct ext4_io_end {

	struct list_head	list;		/* per-file finished IO list */

	handle_t		*handle;	/* handle reserved for extent

						 * conversion */

	struct inode		*inode;		/* file being written to */

	unsigned int		flag;		/* unwritten or not */

	loff_t			offset;		/* offset in the file */
@@ -1322,6 +1325,9 @@ static inline void ext4_set_io_unwritten_flag(struct inode *inode, 
					      struct ext4_io_end *io_end)

{

	if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {

		/* Writeback has to have coversion transaction reserved */

		WARN_ON(EXT4_SB(inode->i_sb)->s_journal && !io_end->handle &&

			!(io_end->flag & EXT4_IO_END_DIRECT));

		io_end->flag |= EXT4_IO_END_UNWRITTEN;

		atomic_inc(&EXT4_I(inode)->i_unwritten);

	}
@@ -2591,8 +2597,8 @@ extern void ext4_ext_init(struct super_block *); 
extern void ext4_ext_release(struct super_block *);

extern long ext4_fallocate(struct file *file, int mode, loff_t offset,

			  loff_t len);

extern int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset,

			  ssize_t len);

extern int ext4_convert_unwritten_extents(handle_t *handle, struct inode *inode,

					  loff_t offset, ssize_t len);

extern int ext4_map_blocks(handle_t *handle, struct inode *inode,

			   struct ext4_map_blocks *map, int flags);

extern int ext4_ext_calc_metadata_amount(struct inode *inode,

fs/ext4/ext4_jbd2.h

+3 −2
Original line number Diff line number Diff line
@@ -134,7 +134,8 @@ static inline int ext4_jbd2_credits_xattr(struct inode *inode) 
#define EXT4_HT_MIGRATE          8

#define EXT4_HT_MOVE_EXTENTS     9

#define EXT4_HT_XATTR           10

#define EXT4_HT_MAX             11

#define EXT4_HT_EXT_CONVERT     11

#define EXT4_HT_MAX             12



/**

 *   struct ext4_journal_cb_entry - Base structure for callback information.
@@ -319,7 +320,7 @@ static inline handle_t *__ext4_journal_start(struct inode *inode, 
#define ext4_journal_stop(handle) \

	__ext4_journal_stop(__func__, __LINE__, (handle))



#define ext4_journal_start_reserve(handle, type) \

#define ext4_journal_start_reserved(handle, type) \

	__ext4_journal_start_reserved((handle), __LINE__, (type))



handle_t *__ext4_journal_start_reserved(handle_t *handle, unsigned int line,

fs/ext4/extents.c

+29 −11
Original line number Diff line number Diff line
@@ -4566,10 +4566,9 @@ retry: 
 * function, to convert the fallocated extents after IO is completed.

 * Returns 0 on success.

 */

int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset,

				    ssize_t len)

int ext4_convert_unwritten_extents(handle_t *handle, struct inode *inode,

				   loff_t offset, ssize_t len)

{

	handle_t *handle;

	unsigned int max_blocks;

	int ret = 0;

	int ret2 = 0;
@@ -4583,18 +4582,34 @@ int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset, 
	 */

	max_blocks = ((EXT4_BLOCK_ALIGN(len + offset, blkbits) >> blkbits) -

		      map.m_lblk);

	/*

	 * This is somewhat ugly but the idea is clear: When transaction is

	 * reserved, everything goes into it. Otherwise we rather start several

	 * smaller transactions for conversion of each extent separately.

	 */

	if (handle) {

		handle = ext4_journal_start_reserved(handle,

						     EXT4_HT_EXT_CONVERT);

		if (IS_ERR(handle))

			return PTR_ERR(handle);

		credits = 0;

	} else {

		/*

		 * credits to insert 1 extent into extent tree

		 */

		credits = ext4_chunk_trans_blocks(inode, max_blocks);

	}

	while (ret >= 0 && ret < max_blocks) {

		map.m_lblk += ret;

		map.m_len = (max_blocks -= ret);

		handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS, credits);

		if (credits) {

			handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS,

						    credits);

			if (IS_ERR(handle)) {

				ret = PTR_ERR(handle);

				break;

			}

		}

		ret = ext4_map_blocks(handle, inode, &map,

				      EXT4_GET_BLOCKS_IO_CONVERT_EXT);

		if (ret <= 0)
@@ -4604,10 +4619,13 @@ int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset, 
				     inode->i_ino, map.m_lblk,

				     map.m_len, ret);

		ext4_mark_inode_dirty(handle, inode);

		if (credits)

			ret2 = ext4_journal_stop(handle);

		if (ret <= 0 || ret2)

			break;

	}

	if (!credits)

		ret2 = ext4_journal_stop(handle);

	return ret > 0 ? ret2 : ret;

}

fs/ext4/inode.c

+20 −5
Original line number Diff line number Diff line
@@ -1410,6 +1410,7 @@ static void ext4_da_page_release_reservation(struct page *page, 
struct mpage_da_data {

	struct inode *inode;

	struct writeback_control *wbc;



	pgoff_t first_page;	/* The first page to write */

	pgoff_t next_page;	/* Current page to examine */

	pgoff_t last_page;	/* Last page to examine */
@@ -2108,8 +2109,14 @@ static int mpage_map_one_extent(handle_t *handle, struct mpage_da_data *mpd) 
	err = ext4_map_blocks(handle, inode, map, get_blocks_flags);

	if (err < 0)

		return err;

	if (map->m_flags & EXT4_MAP_UNINIT)

	if (map->m_flags & EXT4_MAP_UNINIT) {

		if (!mpd->io_submit.io_end->handle &&

		    ext4_handle_valid(handle)) {

			mpd->io_submit.io_end->handle = handle->h_rsv_handle;

			handle->h_rsv_handle = NULL;

		}

		ext4_set_io_unwritten_flag(inode, mpd->io_submit.io_end);

	}



	BUG_ON(map->m_len == 0);

	if (map->m_flags & EXT4_MAP_NEW) {
@@ -2351,7 +2358,7 @@ static int ext4_da_writepages(struct address_space *mapping, 
	handle_t *handle = NULL;

	struct mpage_da_data mpd;

	struct inode *inode = mapping->host;

	int needed_blocks, ret = 0;

	int needed_blocks, rsv_blocks = 0, ret = 0;

	struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);

	bool done;

	struct blk_plug plug;
@@ -2379,6 +2386,14 @@ static int ext4_da_writepages(struct address_space *mapping, 
	if (unlikely(sbi->s_mount_flags & EXT4_MF_FS_ABORTED))

		return -EROFS;



	if (ext4_should_dioread_nolock(inode)) {

		/*

		 * We may need to convert upto one extent per block in

		 * the page and we may dirty the inode.

		 */

		rsv_blocks = 1 + (PAGE_CACHE_SIZE >> inode->i_blkbits);

	}



	/*

	 * If we have inline data and arrive here, it means that

	 * we will soon create the block for the 1st page, so
@@ -2438,8 +2453,8 @@ retry: 
		needed_blocks = ext4_da_writepages_trans_blocks(inode);



		/* start a new transaction */

		handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,

					    needed_blocks);

		handle = ext4_journal_start_with_reserve(inode,

				EXT4_HT_WRITE_PAGE, needed_blocks, rsv_blocks);

		if (IS_ERR(handle)) {

			ret = PTR_ERR(handle);

			ext4_msg(inode->i_sb, KERN_CRIT, "%s: jbd2_start: "
@@ -3120,7 +3135,7 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb, 
		 * for non AIO case, since the IO is already

		 * completed, we could do the conversion right here

		 */

		err = ext4_convert_unwritten_extents(inode,

		err = ext4_convert_unwritten_extents(NULL, inode,

						     offset, ret);

		if (err < 0)

			ret = err;

fs/ext4/page-io.c

+8 −3
Original line number Diff line number Diff line
@@ -66,6 +66,7 @@ static void ext4_release_io_end(ext4_io_end_t *io_end) 
{

	BUG_ON(!list_empty(&io_end->list));

	BUG_ON(io_end->flag & EXT4_IO_END_UNWRITTEN);

	WARN_ON(io_end->handle);



	if (atomic_dec_and_test(&EXT4_I(io_end->inode)->i_ioend_count))

		wake_up_all(ext4_ioend_wq(io_end->inode));
@@ -92,13 +93,15 @@ static int ext4_end_io(ext4_io_end_t *io) 
	struct inode *inode = io->inode;

	loff_t offset = io->offset;

	ssize_t size = io->size;

	handle_t *handle = io->handle;

	int ret = 0;



	ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"

		   "list->prev 0x%p\n",

		   io, inode->i_ino, io->list.next, io->list.prev);



	ret = ext4_convert_unwritten_extents(inode, offset, size);

	io->handle = NULL;	/* Following call will use up the handle */

	ret = ext4_convert_unwritten_extents(handle, inode, offset, size);

	if (ret < 0) {

		ext4_msg(inode->i_sb, KERN_EMERG,

			 "failed to convert unwritten extents to written "
@@ -228,8 +231,10 @@ int ext4_put_io_end(ext4_io_end_t *io_end) 


	if (atomic_dec_and_test(&io_end->count)) {

		if (io_end->flag & EXT4_IO_END_UNWRITTEN) {

			err = ext4_convert_unwritten_extents(io_end->inode,

						io_end->offset, io_end->size);

			err = ext4_convert_unwritten_extents(io_end->handle,

						io_end->inode, io_end->offset,

						io_end->size);

			io_end->handle = NULL;

			ext4_clear_io_unwritten_flag(io_end);

		}

		ext4_release_io_end(io_end);

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