From e84dfbe2bf170c626778079e5b94435b05b8d572 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Fri, 1 Apr 2016 02:07:22 -0400 Subject: [PATCH] ext4: retry block allocation for failed DIO and DAX writes Currently if block allocation for DIO or DAX write fails due to ENOSPC, we just returned it to userspace. However these ENOSPC errors can be transient because the transaction freeing blocks has not yet committed. This demonstrates as failures of generic/102 test when the filesystem is mounted with 'dax' mount option. Fix the problem by properly retrying the allocation in case of ENOSPC error in get blocks functions used for direct IO. Signed-off-by: Jan Kara Signed-off-by: Theodore Ts'o Tested-by: Ross Zwisler --- fs/ext4/inode.c | 58 ++++++++++++++++++++++++------------------------- 1 file changed, 28 insertions(+), 30 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index dab84a2530ff..8710174090f5 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -763,39 +763,47 @@ int ext4_get_block_unwritten(struct inode *inode, sector_t iblock, /* Maximum number of blocks we map for direct IO at once. */ #define DIO_MAX_BLOCKS 4096 -static handle_t *start_dio_trans(struct inode *inode, - struct buffer_head *bh_result) +/* + * Get blocks function for the cases that need to start a transaction - + * generally difference cases of direct IO and DAX IO. It also handles retries + * in case of ENOSPC. + */ +static int ext4_get_block_trans(struct inode *inode, sector_t iblock, + struct buffer_head *bh_result, int flags) { int dio_credits; + handle_t *handle; + int retries = 0; + int ret; /* Trim mapping request to maximum we can map at once for DIO */ if (bh_result->b_size >> inode->i_blkbits > DIO_MAX_BLOCKS) bh_result->b_size = DIO_MAX_BLOCKS << inode->i_blkbits; dio_credits = ext4_chunk_trans_blocks(inode, bh_result->b_size >> inode->i_blkbits); - return ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS, dio_credits); +retry: + handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS, dio_credits); + if (IS_ERR(handle)) + return PTR_ERR(handle); + + ret = _ext4_get_block(inode, iblock, bh_result, flags); + ext4_journal_stop(handle); + + if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries)) + goto retry; + return ret; } /* Get block function for DIO reads and writes to inodes without extents */ int ext4_dio_get_block(struct inode *inode, sector_t iblock, struct buffer_head *bh, int create) { - handle_t *handle; - int ret; - /* We don't expect handle for direct IO */ WARN_ON_ONCE(ext4_journal_current_handle()); - if (create) { - handle = start_dio_trans(inode, bh); - if (IS_ERR(handle)) - return PTR_ERR(handle); - } - ret = _ext4_get_block(inode, iblock, bh, - create ? EXT4_GET_BLOCKS_CREATE : 0); - if (create) - ext4_journal_stop(handle); - return ret; + if (!create) + return _ext4_get_block(inode, iblock, bh, 0); + return ext4_get_block_trans(inode, iblock, bh, EXT4_GET_BLOCKS_CREATE); } /* @@ -806,18 +814,13 @@ int ext4_dio_get_block(struct inode *inode, sector_t iblock, static int ext4_dio_get_block_unwritten_async(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create) { - handle_t *handle; int ret; /* We don't expect handle for direct IO */ WARN_ON_ONCE(ext4_journal_current_handle()); - handle = start_dio_trans(inode, bh_result); - if (IS_ERR(handle)) - return PTR_ERR(handle); - ret = _ext4_get_block(inode, iblock, bh_result, - EXT4_GET_BLOCKS_IO_CREATE_EXT); - ext4_journal_stop(handle); + ret = ext4_get_block_trans(inode, iblock, bh_result, + EXT4_GET_BLOCKS_IO_CREATE_EXT); /* * When doing DIO using unwritten extents, we need io_end to convert @@ -850,18 +853,13 @@ static int ext4_dio_get_block_unwritten_async(struct inode *inode, static int ext4_dio_get_block_unwritten_sync(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create) { - handle_t *handle; int ret; /* We don't expect handle for direct IO */ WARN_ON_ONCE(ext4_journal_current_handle()); - handle = start_dio_trans(inode, bh_result); - if (IS_ERR(handle)) - return PTR_ERR(handle); - ret = _ext4_get_block(inode, iblock, bh_result, - EXT4_GET_BLOCKS_IO_CREATE_EXT); - ext4_journal_stop(handle); + ret = ext4_get_block_trans(inode, iblock, bh_result, + EXT4_GET_BLOCKS_IO_CREATE_EXT); /* * Mark inode as having pending DIO writes to unwritten extents. -- 2.39.5