The ->iomap_begin() operation is a hot path, so cache the fs_dax_get_by_host() result to avoid the incurring the hash lookup overhead.
Cc: Jan Kara <[email protected]> Cc: "Theodore Ts'o" <[email protected]> Cc: Andreas Dilger <[email protected]> Reported-by: Christoph Hellwig <[email protected]> Signed-off-by: Dan Williams <[email protected]> --- fs/ext2/inode.c | 11 +++++++---- fs/ext4/inode.c | 11 +++++++---- include/linux/fs.h | 3 +++ 3 files changed, 17 insertions(+), 8 deletions(-) diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c index 30163d007b2f..910e6d502137 100644 --- a/fs/ext2/inode.c +++ b/fs/ext2/inode.c @@ -801,6 +801,7 @@ static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length, unsigned flags, struct iomap *iomap) { struct block_device *bdev; + struct dax_device *dax_dev; unsigned int blkbits = inode->i_blkbits; unsigned long first_block = offset >> blkbits; unsigned long max_blocks = (length + (1 << blkbits) - 1) >> blkbits; @@ -817,10 +818,12 @@ static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length, bdev = inode->i_sb->s_bdev; iomap->bdev = bdev; iomap->offset = (u64)first_block << blkbits; - 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; + dax_dev = inode->i_sb->s_daxdev; + if (blk_queue_dax(bdev->bd_queue) && !dax_dev) { + dax_dev = fs_dax_get_by_host(bdev->bd_disk->disk_name); + inode->i_sb->s_daxdev = dax_dev; + } + iomap->dax_dev = dax_dev; if (ret == 0) { iomap->type = IOMAP_HOLE; diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index c774bdc22759..36a4bcab9e0c 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3405,6 +3405,7 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length, unsigned flags, struct iomap *iomap) { struct block_device *bdev; + struct dax_device *dax_dev; unsigned int blkbits = inode->i_blkbits; unsigned long first_block = offset >> blkbits; unsigned long last_block = (offset + length - 1) >> blkbits; @@ -3475,10 +3476,12 @@ 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; + dax_dev = inode->i_sb->s_daxdev; + if (blk_queue_dax(bdev->bd_queue) && !dax_dev) { + dax_dev = fs_dax_get_by_host(bdev->bd_disk->disk_name); + inode->i_sb->s_daxdev = dax_dev; + } + iomap->dax_dev = dax_dev; iomap->offset = first_block << blkbits; if (ret == 0) { diff --git a/include/linux/fs.h b/include/linux/fs.h index 6e1fd5d21248..0594867a172a 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1334,6 +1334,9 @@ struct super_block { struct hlist_bl_head s_anon; /* anonymous dentries for (nfs) exporting */ struct list_head s_mounts; /* list of mounts; _not_ for fs use */ struct block_device *s_bdev; +#ifdef CONFIG_FS_DAX + struct dax_device *s_daxdev; /* cached dax_device */ +#endif struct backing_dev_info *s_bdi; struct mtd_info *s_mtd; struct hlist_node s_instances; _______________________________________________ Linux-nvdimm mailing list [email protected] https://lists.01.org/mailman/listinfo/linux-nvdimm
