Implement basic iomap_begin function that handles reading and use it for DAX reads.
Signed-off-by: Jan Kara <[email protected]> --- fs/ext4/ext4.h | 2 ++ fs/ext4/file.c | 40 +++++++++++++++++++++++++++++++++++++++- fs/ext4/inode.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 95 insertions(+), 1 deletion(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 282a51b07c57..098b39910001 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -3271,6 +3271,8 @@ static inline bool ext4_aligned_io(struct inode *inode, loff_t off, loff_t len) return IS_ALIGNED(off, blksize) && IS_ALIGNED(len, blksize); } +extern struct iomap_ops ext4_iomap_ops; + #endif /* __KERNEL__ */ #define EFSBADCRC EBADMSG /* Bad CRC detected */ diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 55f8b922b76d..28ebc2418dc2 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -31,6 +31,44 @@ #include "xattr.h" #include "acl.h" +#ifdef CONFIG_FS_DAX +static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to) +{ + struct inode *inode = iocb->ki_filp->f_mapping->host; + ssize_t ret; + + inode_lock_shared(inode); + /* + * Recheck under inode lock - at this point we are sure it cannot + * change anymore + */ + if (!IS_DAX(inode)) { + inode_unlock_shared(inode); + /* Fallback to buffered IO in case we cannot support DAX */ + return generic_file_read_iter(iocb, to); + } + ret = dax_iomap_rw(iocb, to, &ext4_iomap_ops); + inode_unlock_shared(inode); + + file_accessed(iocb->ki_filp); + return ret; +} +#endif + +static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to) +{ + struct inode *inode = iocb->ki_filp->f_mapping->host; + + if (!iov_iter_count(to)) + return 0; /* skip atime */ + +#ifdef CONFIG_FS_DAX + if (IS_DAX(inode)) + return ext4_dax_read_iter(iocb, to); +#endif + return generic_file_read_iter(iocb, to); +} + /* * Called when an inode is released. Note that this is different * from ext4_file_open: open gets called at every open, but release @@ -691,7 +729,7 @@ loff_t ext4_llseek(struct file *file, loff_t offset, int whence) const struct file_operations ext4_file_operations = { .llseek = ext4_llseek, - .read_iter = generic_file_read_iter, + .read_iter = ext4_file_read_iter, .write_iter = ext4_file_write_iter, .unlocked_ioctl = ext4_ioctl, #ifdef CONFIG_COMPAT diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 4cbd1b24c237..cc10145ea98b 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -37,6 +37,7 @@ #include <linux/printk.h> #include <linux/slab.h> #include <linux/bitops.h> +#include <linux/iomap.h> #include "ext4_jbd2.h" #include "xattr.h" @@ -3305,6 +3306,59 @@ int ext4_dax_get_block(struct inode *inode, sector_t iblock, clear_buffer_new(bh_result); return 0; } + +static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length, + unsigned flags, struct iomap *iomap) +{ + unsigned int blkbits = inode->i_blkbits; + unsigned long first_block = offset >> blkbits; + unsigned long last_block = (offset + length - 1) >> blkbits; + struct ext4_map_blocks map; + int ret; + + if (flags & IOMAP_WRITE) + return -EIO; + + if (WARN_ON_ONCE(ext4_has_inline_data(inode))) + return -ERANGE; + + map.m_lblk = first_block; + map.m_len = last_block - first_block + 1; + + ret = ext4_map_blocks(NULL, inode, &map, 0); + if (ret < 0) + return ret; + + iomap->flags = 0; + iomap->bdev = inode->i_sb->s_bdev; + iomap->offset = first_block << blkbits; + + if (ret == 0) { + iomap->type = IOMAP_HOLE; + iomap->blkno = IOMAP_NULL_BLOCK; + iomap->length = (u64)map.m_len << blkbits; + } else { + if (map.m_flags & EXT4_MAP_MAPPED) { + iomap->type = IOMAP_MAPPED; + } else if (map.m_flags & EXT4_MAP_UNWRITTEN) { + iomap->type = IOMAP_UNWRITTEN; + } else { + WARN_ON_ONCE(1); + return -EIO; + } + iomap->blkno = (sector_t)map.m_pblk << (blkbits - 9); + iomap->length = (u64)map.m_len << blkbits; + } + + if (map.m_flags & EXT4_MAP_NEW) + iomap->flags |= IOMAP_F_NEW; + return 0; +} + +struct iomap_ops ext4_iomap_ops = { + .iomap_begin = ext4_iomap_begin, +}; + #else /* Just define empty function, it will never get called. */ int ext4_dax_get_block(struct inode *inode, sector_t iblock, -- 2.6.6 _______________________________________________ Linux-nvdimm mailing list [email protected] https://lists.01.org/mailman/listinfo/linux-nvdimm
