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Commit 5e405595 authored by Dan Williams's avatar Dan Williams
Browse files

ext4: perform dax_device lookup at mount 



The ->iomap_begin() operation is a hot path, so cache the
fs_dax_get_by_host() result at mount time to avoid the incurring the
hash lookup overhead on a per-i/o basis.

Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Reported-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent 8cf037a8

fs/ext4/ext4.h

+1 −0
Original line number Diff line number Diff line
@@ -1528,6 +1528,7 @@ struct ext4_sb_info { 


	/* Barrier between changing inodes' journal flags and writepages ops. */

	struct percpu_rw_semaphore s_journal_flag_rwsem;

	struct dax_device *s_daxdev;

};



static inline struct ext4_sb_info *EXT4_SB(struct super_block *sb)

fs/ext4/inode.c

+3 −8
Original line number Diff line number Diff line
@@ -3404,7 +3404,7 @@ static int ext4_releasepage(struct page *page, gfp_t wait) 
static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,

			    unsigned flags, struct iomap *iomap)

{

	struct block_device *bdev;

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

	unsigned int blkbits = inode->i_blkbits;

	unsigned long first_block = offset >> blkbits;

	unsigned long last_block = (offset + length - 1) >> blkbits;
@@ -3473,12 +3473,8 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length, 
	}



	iomap->flags = 0;

	bdev = inode->i_sb->s_bdev;

	iomap->bdev = bdev;

	if (blk_queue_dax(bdev->bd_queue))

		iomap->dax_dev = fs_dax_get_by_host(bdev->bd_disk->disk_name);

	else

		iomap->dax_dev = NULL;

	iomap->bdev = inode->i_sb->s_bdev;

	iomap->dax_dev = sbi->s_daxdev;

	iomap->offset = first_block << blkbits;



	if (ret == 0) {
@@ -3511,7 +3507,6 @@ static int ext4_iomap_end(struct inode *inode, loff_t offset, loff_t length, 
	int blkbits = inode->i_blkbits;

	bool truncate = false;



	fs_put_dax(iomap->dax_dev);

	if (!(flags & IOMAP_WRITE) || (flags & IOMAP_FAULT))

		return 0;

fs/ext4/super.c

+4 −0
Original line number Diff line number Diff line
@@ -951,6 +951,7 @@ static void ext4_put_super(struct super_block *sb) 
	if (sbi->s_chksum_driver)

		crypto_free_shash(sbi->s_chksum_driver);

	kfree(sbi->s_blockgroup_lock);

	fs_put_dax(sbi->s_daxdev);

	kfree(sbi);

}
@@ -3377,6 +3378,7 @@ static void ext4_set_resv_clusters(struct super_block *sb) 


static int ext4_fill_super(struct super_block *sb, void *data, int silent)

{

	struct dax_device *dax_dev = fs_dax_get_by_bdev(sb->s_bdev);

	char *orig_data = kstrdup(data, GFP_KERNEL);

	struct buffer_head *bh;

	struct ext4_super_block *es = NULL;
@@ -3399,6 +3401,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) 
	unsigned int journal_ioprio = DEFAULT_JOURNAL_IOPRIO;

	ext4_group_t first_not_zeroed;



	sbi->s_daxdev = dax_dev;

	if ((data && !orig_data) || !sbi)

		goto out_free_base;
@@ -4378,6 +4381,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) 
out_free_base:

	kfree(sbi);

	kfree(orig_data);

	fs_put_dax(dax_dev);

	return err ? err : ret;

}