diff options
| -rw-r--r-- | fs/ext4/ext4.h | 3 | ||||
| -rw-r--r-- | fs/ext4/inode.c | 197 | ||||
| -rw-r--r-- | fs/ext4/super.c | 11 |
3 files changed, 210 insertions, 1 deletions
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 2b4293aac162..ccb4dbf359c4 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -999,6 +999,9 @@ struct ext4_sb_info { unsigned int s_log_groups_per_flex; struct flex_groups *s_flex_groups; + + /* workqueue for dio unwritten */ + struct workqueue_struct *dio_unwritten_wq; }; static inline struct ext4_sb_info *EXT4_SB(struct super_block *sb) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index da4f2ecb5447..5633af6a7045 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -37,6 +37,7 @@ #include <linux/namei.h> #include <linux/uio.h> #include <linux/bio.h> +#include <linux/workqueue.h> #include "ext4_jbd2.h" #include "xattr.h" @@ -3356,6 +3357,8 @@ static int ext4_releasepage(struct page *page, gfp_t wait) } /* + * O_DIRECT for ext3 (or indirect map) based files + * * If the O_DIRECT write will extend the file then add this inode to the * orphan list. So recovery will truncate it back to the original size * if the machine crashes during the write. @@ -3364,7 +3367,7 @@ static int ext4_releasepage(struct page *page, gfp_t wait) * crashes then stale disk data _may_ be exposed inside the file. But current * VFS code falls back into buffered path in that case so we are safe. */ -static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb, +static ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t offset, unsigned long nr_segs) { @@ -3438,6 +3441,198 @@ out: return ret; } +/* Maximum number of blocks we map for direct IO at once. */ + +static int ext4_get_block_dio_write(struct inode *inode, sector_t iblock, + struct buffer_head *bh_result, int create) +{ + handle_t *handle = NULL; + int ret = 0; + unsigned max_blocks = bh_result->b_size >> inode->i_blkbits; + int dio_credits; + + /* + * DIO VFS code passes create = 0 flag for write to + * the middle of file. It does this to avoid block + * allocation for holes, to prevent expose stale data + * out when there is parallel buffered read (which does + * not hold the i_mutex lock) while direct IO write has + * not completed. DIO request on holes finally falls back + * to buffered IO for this reason. + * + * For ext4 extent based file, since we support fallocate, + * new allocated extent as uninitialized, for holes, we + * could fallocate blocks for holes, thus parallel + * buffered IO read will zero out the page when read on + * a hole while parallel DIO write to the hole has not completed. + * + * when we come here, we know it's a direct IO write to + * to the middle of file (<i_size) + * so it's safe to override the create flag from VFS. + */ + create = EXT4_GET_BLOCKS_DIO_CREATE_EXT; + + if (max_blocks > DIO_MAX_BLOCKS) + max_blocks = DIO_MAX_BLOCKS; + dio_credits = ext4_chunk_trans_blocks(inode, max_blocks); + handle = ext4_journal_start(inode, dio_credits); + if (IS_ERR(handle)) { + ret = PTR_ERR(handle); + goto out; + } + ret = ext4_get_blocks(handle, inode, iblock, max_blocks, bh_result, + create); + if (ret > 0) { + bh_result->b_size = (ret << inode->i_blkbits); + ret = 0; + } + ext4_journal_stop(handle); +out: + return ret; +} + +#define DIO_AIO 0x1 + +static void ext4_free_io_end(ext4_io_end_t *io) +{ + kfree(io); +} + +/* + * IO write completion for unwritten extents. + * + * check a range of space and convert unwritten extents to written. + */ +static void ext4_end_dio_unwritten(struct work_struct *work) +{ + ext4_io_end_t *io = container_of(work, ext4_io_end_t, work); + struct inode *inode = io->inode; + loff_t offset = io->offset; + size_t size = io->size; + int ret = 0; + int aio = io->flag & DIO_AIO; + + if (aio) + mutex_lock(&inode->i_mutex); + if (offset + size <= i_size_read(inode)) + ret = ext4_convert_unwritten_extents(inode, offset, size); + + if (ret < 0) + printk(KERN_EMERG "%s: failed to convert unwritten" + "extents to written extents, error is %d\n", + __func__, ret); + + ext4_free_io_end(io); + if (aio) + mutex_unlock(&inode->i_mutex); +} + +static ext4_io_end_t *ext4_init_io_end (struct inode *inode, unsigned int flag) +{ + ext4_io_end_t *io = NULL; + + io = kmalloc(sizeof(*io), GFP_NOFS); + + if (io) { + io->inode = inode; + io->flag = flag; + io->offset = 0; + io->size = 0; + io->error = 0; + INIT_WORK(&io->work, ext4_end_dio_unwritten); + } + + return io; +} + +static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset, + ssize_t size, void *private) +{ + ext4_io_end_t *io_end = iocb->private; + struct workqueue_struct *wq; + + /* if not hole or unwritten extents, just simple return */ + if (!io_end || !size || !iocb->private) + return; + io_end->offset = offset; + io_end->size = size; + wq = EXT4_SB(io_end->inode->i_sb)->dio_unwritten_wq; + + /* We need to convert unwritten extents to written */ + queue_work(wq, &io_end->work); + + if (is_sync_kiocb(iocb)) + flush_workqueue(wq); + + iocb->private = NULL; +} +/* + * For ext4 extent files, ext4 will do direct-io write to holes, + * preallocated extents, and those write extend the file, no need to + * fall back to buffered IO. + * + * For holes, we fallocate those blocks, mark them as unintialized + * If those blocks were preallocated, we mark sure they are splited, but + * still keep the range to write as unintialized. + * + * When end_io call back function called at the last IO complete time, + * those extents will be converted to written extents. + * + * If the O_DIRECT write will extend the file then add this inode to the + * orphan list. So recovery will truncate it back to the original size + * if the machine crashes during the write. + * + */ +static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb, + const struct iovec *iov, loff_t offset, + unsigned long nr_segs) +{ + struct file *file = iocb->ki_filp; + struct inode *inode = file->f_mapping->host; + ssize_t ret; + size_t count = iov_length(iov, nr_segs); + + loff_t final_size = offset + count; + if (rw == WRITE && final_size <= inode->i_size) { + /* + * For DIO we fallocate blocks for holes, we fallocate blocks + * The fallocated extent for hole is marked as uninitialized + * to prevent paralel buffered read to expose the stale data + * before DIO complete the data IO. + * as for previously fallocated extents, ext4 get_block + * will just simply mark the buffer mapped but still + * keep the extents uninitialized. + * + * At the end of IO, the ext4 end_io callback function + * will convert those unwritten extents to written, + * + */ + iocb->private = ext4_init_io_end(inode, !is_sync_kiocb(iocb)); + if (!iocb->private) + return -ENOMEM; + ret = blockdev_direct_IO(rw, iocb, inode, + inode->i_sb->s_bdev, iov, + offset, nr_segs, + ext4_get_block_dio_write, + ext4_end_io_dio); + return ret; + } + return ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs); +} + +static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb, + const struct iovec *iov, loff_t offset, + unsigned long nr_segs) +{ + struct file *file = iocb->ki_filp; + struct inode *inode = file->f_mapping->host; + + if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) + return ext4_ext_direct_IO(rw, iocb, iov, offset, nr_segs); + + return ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs); +} + /* * Pages can be marked dirty completely asynchronously from ext4's journalling * activity. By filemap_sync_pte(), try_to_unmap_one(), etc. We cannot do diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 16817737ba52..1a03ea98fdd1 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -580,6 +580,9 @@ static void ext4_put_super(struct super_block *sb) struct ext4_super_block *es = sbi->s_es; int i, err; + flush_workqueue(sbi->dio_unwritten_wq); + destroy_workqueue(sbi->dio_unwritten_wq); + lock_super(sb); lock_kernel(); if (sb->s_dirt) @@ -2801,6 +2804,12 @@ no_journal: clear_opt(sbi->s_mount_opt, NOBH); } } + EXT4_SB(sb)->dio_unwritten_wq = create_workqueue("ext4-dio-unwritten"); + if (!EXT4_SB(sb)->dio_unwritten_wq) { + printk(KERN_ERR "EXT4-fs: failed to create DIO workqueue\n"); + goto failed_mount_wq; + } + /* * The jbd2_journal_load will have done any necessary log recovery, * so we can safely mount the rest of the filesystem now. @@ -2913,6 +2922,8 @@ cantfind_ext4: failed_mount4: ext4_msg(sb, KERN_ERR, "mount failed"); + destroy_workqueue(EXT4_SB(sb)->dio_unwritten_wq); +failed_mount_wq: ext4_release_system_zone(sb); if (sbi->s_journal) { jbd2_journal_destroy(sbi->s_journal); |