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Date: Fri, 18 Nov 2016 09:47:03 +0100
From: Jan Kara <jack@...e.cz>
To: Ted Tso <tytso@....edu>
Cc: <linux-ext4@...r.kernel.org>,
Ross Zwisler <ross.zwisler@...ux.intel.com>,
Jan Kara <jack@...e.cz>
Subject: [PATCH 03/10] ext4: Convert DAX reads to iomap infrastructure
Implement basic iomap_begin function that handles reading and use it for
DAX reads.
Reviewed-by: Ross Zwisler <ross.zwisler@...ux.intel.com>
Signed-off-by: Jan Kara <jack@...e.cz>
---
fs/ext4/ext4.h | 2 ++
fs/ext4/file.c | 38 +++++++++++++++++++++++++++++++++++++-
fs/ext4/inode.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 93 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 9facb4dc5c70..1f25c644cb12 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -31,6 +31,42 @@
#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 = file_inode(iocb->ki_filp);
+ 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)
+{
+ if (!iov_iter_count(to))
+ return 0; /* skip atime */
+
+#ifdef CONFIG_FS_DAX
+ if (IS_DAX(file_inode(iocb->ki_filp)))
+ 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
@@ -690,7 +726,7 @@ 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 5337828c68a7..83e8411370d3 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"
@@ -3310,6 +3311,59 @@ 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
--
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