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ext4: perform dax_device lookup at mount

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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: Jan Kara <jack@suse.cz>
Reported-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams 2017-08-24 16:42:48 -07:00
parent 8cf037a8b2
commit 5e405595e5
3 changed files with 8 additions and 8 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

1
fs/ext4/ext4.h
View file

@ -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)

11
fs/ext4/inode.c
View file

@ -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;

4
fs/ext4/super.c
View file

@ -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;
}