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ext4: use transaction reservation for extent conversion in ext4_end_io

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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: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Jan Kara
2013-06-04 13:21:11 -04:00
committed by Theodore Ts'o
parent 3613d22807
commit 6b523df4fb
5 changed files with 69 additions and 24 deletions
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12
fs/ext4/ext4.h
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@ -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,