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Subject[PATCH v7 20/22] ext4: Add DAX functionality
Date
From: Ross Zwisler <ross.zwisler@linux.intel.com>

This is a port of the DAX functionality found in the current version of
ext2.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
[heavily tweaked]
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
---
Documentation/filesystems/dax.txt | 1 +
Documentation/filesystems/ext4.txt | 2 ++
fs/ext4/ext4.h | 6 +++++
fs/ext4/file.c | 53 +++++++++++++++++++++++++++++++++-----
fs/ext4/indirect.c | 19 +++++++++-----
fs/ext4/inode.c | 52 ++++++++++++++++++++++++-------------
fs/ext4/namei.c | 10 +++++--
fs/ext4/super.c | 39 +++++++++++++++++++++++++++-
8 files changed, 149 insertions(+), 33 deletions(-)

diff --git a/Documentation/filesystems/dax.txt b/Documentation/filesystems/dax.txt
index e5706cc..619dab5 100644
--- a/Documentation/filesystems/dax.txt
+++ b/Documentation/filesystems/dax.txt
@@ -66,6 +66,7 @@ or a write()) work correctly.

These filesystems may be used for inspiration:
- ext2: the second extended filesystem, see Documentation/filesystems/ext2.txt
+- ext4: the fourth extended filesystem, see Documentation/filesystems/ext4.txt


Shortcomings
diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt
index 919a329..9c511c4 100644
--- a/Documentation/filesystems/ext4.txt
+++ b/Documentation/filesystems/ext4.txt
@@ -386,6 +386,8 @@ max_dir_size_kb=n This limits the size of directories so that any
i_version Enable 64-bit inode version support. This option is
off by default.

+dax Use direct access if possible
+
Data Mode
=========
There are 3 different data modes:
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index e025c29..00e9b79 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -966,6 +966,11 @@ struct ext4_inode_info {
#define EXT4_MOUNT_ERRORS_MASK 0x00070
#define EXT4_MOUNT_MINIX_DF 0x00080 /* Mimics the Minix statfs */
#define EXT4_MOUNT_NOLOAD 0x00100 /* Don't use existing journal*/
+#ifdef CONFIG_FS_DAX
+#define EXT4_MOUNT_DAX 0x00200 /* Execute in place */
+#else
+#define EXT4_MOUNT_DAX 0
+#endif
#define EXT4_MOUNT_DATA_FLAGS 0x00C00 /* Mode for data writes: */
#define EXT4_MOUNT_JOURNAL_DATA 0x00400 /* Write data to journal */
#define EXT4_MOUNT_ORDERED_DATA 0x00800 /* Flush data before commit */
@@ -2581,6 +2586,7 @@ extern const struct file_operations ext4_dir_operations;
/* file.c */
extern const struct inode_operations ext4_file_inode_operations;
extern const struct file_operations ext4_file_operations;
+extern const struct file_operations ext4_dax_file_operations;
extern loff_t ext4_llseek(struct file *file, loff_t offset, int origin);
extern void ext4_unwritten_wait(struct inode *inode);

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 1a50739..42a8ccd 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -190,7 +190,7 @@ ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
}
}

- if (unlikely(iocb->ki_filp->f_flags & O_DIRECT))
+ if (io_is_direct(iocb->ki_filp))
ret = ext4_file_dio_write(iocb, iov, nr_segs, pos);
else
ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
@@ -198,6 +198,27 @@ ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
return ret;
}

+#ifdef CONFIG_FS_DAX
+static int ext4_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+ return dax_fault(vma, vmf, ext4_get_block);
+ /* Is this the right get_block? */
+}
+
+static int ext4_dax_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+ return dax_mkwrite(vma, vmf, ext4_get_block);
+}
+
+static const struct vm_operations_struct ext4_dax_vm_ops = {
+ .fault = ext4_dax_fault,
+ .page_mkwrite = ext4_dax_mkwrite,
+ .remap_pages = generic_file_remap_pages,
+};
+#else
+#define ext4_dax_vm_ops ext4_file_vm_ops
+#endif
+
static const struct vm_operations_struct ext4_file_vm_ops = {
.fault = filemap_fault,
.page_mkwrite = ext4_page_mkwrite,
@@ -206,12 +227,13 @@ static const struct vm_operations_struct ext4_file_vm_ops = {

static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
{
- struct address_space *mapping = file->f_mapping;
-
- if (!mapping->a_ops->readpage)
- return -ENOEXEC;
file_accessed(file);
- vma->vm_ops = &ext4_file_vm_ops;
+ if (IS_DAX(file_inode(file))) {
+ vma->vm_ops = &ext4_dax_vm_ops;
+ vma->vm_flags |= VM_MIXEDMAP;
+ } else {
+ vma->vm_ops = &ext4_file_vm_ops;
+ }
return 0;
}

@@ -609,6 +631,25 @@ const struct file_operations ext4_file_operations = {
.fallocate = ext4_fallocate,
};

+#ifdef CONFIG_FS_DAX
+const struct file_operations ext4_dax_file_operations = {
+ .llseek = ext4_llseek,
+ .read = do_sync_read,
+ .write = do_sync_write,
+ .aio_read = generic_file_aio_read,
+ .aio_write = ext4_file_write,
+ .unlocked_ioctl = ext4_ioctl,
+#ifdef CONFIG_COMPAT
+ .compat_ioctl = ext4_compat_ioctl,
+#endif
+ .mmap = ext4_file_mmap,
+ .open = ext4_file_open,
+ .release = ext4_release_file,
+ .fsync = ext4_sync_file,
+ .fallocate = ext4_fallocate,
+};
+#endif
+
const struct inode_operations ext4_file_inode_operations = {
.setattr = ext4_setattr,
.getattr = ext4_getattr,
diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
index 594009f..5fdb414 100644
--- a/fs/ext4/indirect.c
+++ b/fs/ext4/indirect.c
@@ -686,15 +686,22 @@ retry:
inode_dio_done(inode);
goto locked;
}
- ret = __blockdev_direct_IO(rw, iocb, inode,
- inode->i_sb->s_bdev, iov,
- offset, nr_segs,
- ext4_get_block, NULL, NULL, 0);
+ if (IS_DAX(inode))
+ ret = dax_do_io(rw, iocb, inode, iov, offset, nr_segs,
+ ext4_get_block, NULL, 0);
+ else
+ ret = __blockdev_direct_IO(rw, iocb, inode,
+ inode->i_sb->s_bdev, iov, offset,
+ nr_segs, ext4_get_block, NULL, NULL, 0);
inode_dio_done(inode);
} else {
locked:
- ret = blockdev_direct_IO(rw, iocb, inode, iov,
- offset, nr_segs, ext4_get_block);
+ if (IS_DAX(inode))
+ ret = dax_do_io(rw, iocb, inode, iov, offset, nr_segs,
+ ext4_get_block, NULL, DIO_LOCKING);
+ else
+ ret = blockdev_direct_IO(rw, iocb, inode, iov,
+ offset, nr_segs, ext4_get_block);

if (unlikely((rw & WRITE) && ret < 0)) {
loff_t isize = i_size_read(inode);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index ce7341c..9462730 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3140,13 +3140,14 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
get_block_func = ext4_get_block_write;
dio_flags = DIO_LOCKING;
}
- ret = __blockdev_direct_IO(rw, iocb, inode,
- inode->i_sb->s_bdev, iov,
- offset, nr_segs,
- get_block_func,
- ext4_end_io_dio,
- NULL,
- dio_flags);
+ if (IS_DAX(inode))
+ ret = dax_do_io(rw, iocb, inode, iov, offset, nr_segs,
+ get_block_func, ext4_end_io_dio, dio_flags);
+ else
+ ret = __blockdev_direct_IO(rw, iocb, inode,
+ inode->i_sb->s_bdev, iov, offset,
+ nr_segs, get_block_func,
+ ext4_end_io_dio, NULL, dio_flags);

/*
* Put our reference to io_end. This can free the io_end structure e.g.
@@ -3311,14 +3312,7 @@ void ext4_set_aops(struct inode *inode)
inode->i_mapping->a_ops = &ext4_aops;
}

-/*
- * ext4_block_zero_page_range() zeros out a mapping of length 'length'
- * starting from file offset 'from'. The range to be zero'd must
- * be contained with in one block. If the specified range exceeds
- * the end of the block it will be shortened to end of the block
- * that cooresponds to 'from'
- */
-static int ext4_block_zero_page_range(handle_t *handle,
+static int __ext4_block_zero_page_range(handle_t *handle,
struct address_space *mapping, loff_t from, loff_t length)
{
ext4_fsblk_t index = from >> PAGE_CACHE_SHIFT;
@@ -3409,6 +3403,22 @@ unlock:
}

/*
+ * ext4_block_zero_page_range() zeros out a mapping of length 'length'
+ * starting from file offset 'from'. The range to be zero'd must
+ * be contained with in one block. If the specified range exceeds
+ * the end of the block it will be shortened to end of the block
+ * that cooresponds to 'from'
+ */
+static int ext4_block_zero_page_range(handle_t *handle,
+ struct address_space *mapping, loff_t from, loff_t length)
+{
+ struct inode *inode = mapping->host;
+ if (IS_DAX(inode))
+ return dax_zero_page_range(inode, from, length, ext4_get_block);
+ return __ext4_block_zero_page_range(handle, mapping, from, length);
+}
+
+/*
* ext4_block_truncate_page() zeroes out a mapping from file offset `from'
* up to the end of the block which corresponds to `from'.
* This required during truncate. We need to physically zero the tail end
@@ -3922,7 +3932,8 @@ void ext4_set_inode_flags(struct inode *inode)
{
unsigned int flags = EXT4_I(inode)->i_flags;

- inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
+ inode->i_flags &= ~(S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME |
+ S_DIRSYNC | S_DAX);
if (flags & EXT4_SYNC_FL)
inode->i_flags |= S_SYNC;
if (flags & EXT4_APPEND_FL)
@@ -3933,6 +3944,8 @@ void ext4_set_inode_flags(struct inode *inode)
inode->i_flags |= S_NOATIME;
if (flags & EXT4_DIRSYNC_FL)
inode->i_flags |= S_DIRSYNC;
+ if (test_opt(inode->i_sb, DAX))
+ inode->i_flags |= S_DAX;
}

/* Propagate flags from i_flags to EXT4_I(inode)->i_flags */
@@ -4184,7 +4197,10 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)

if (S_ISREG(inode->i_mode)) {
inode->i_op = &ext4_file_inode_operations;
- inode->i_fop = &ext4_file_operations;
+ if (test_opt(inode->i_sb, DAX))
+ inode->i_fop = &ext4_dax_file_operations;
+ else
+ inode->i_fop = &ext4_file_operations;
ext4_set_aops(inode);
} else if (S_ISDIR(inode->i_mode)) {
inode->i_op = &ext4_dir_inode_operations;
@@ -4640,7 +4656,7 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
* Truncate pagecache after we've waited for commit
* in data=journal mode to make pages freeable.
*/
- truncate_pagecache(inode, inode->i_size);
+ truncate_pagecache(inode, inode->i_size);
}
/*
* We want to call ext4_truncate() even if attr->ia_size ==
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index d050e04..acb9cca 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2249,7 +2249,10 @@ retry:
err = PTR_ERR(inode);
if (!IS_ERR(inode)) {
inode->i_op = &ext4_file_inode_operations;
- inode->i_fop = &ext4_file_operations;
+ if (test_opt(inode->i_sb, DAX))
+ inode->i_fop = &ext4_dax_file_operations;
+ else
+ inode->i_fop = &ext4_file_operations;
ext4_set_aops(inode);
err = ext4_add_nondir(handle, dentry, inode);
if (!err && IS_DIRSYNC(dir))
@@ -2313,7 +2316,10 @@ retry:
err = PTR_ERR(inode);
if (!IS_ERR(inode)) {
inode->i_op = &ext4_file_inode_operations;
- inode->i_fop = &ext4_file_operations;
+ if (test_opt(inode->i_sb, DAX))
+ inode->i_fop = &ext4_dax_file_operations;
+ else
+ inode->i_fop = &ext4_file_operations;
ext4_set_aops(inode);
d_tmpfile(dentry, inode);
err = ext4_orphan_add(handle, inode);
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 710fed2..c0b7f4c 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1156,7 +1156,7 @@ enum {
Opt_usrjquota, Opt_grpjquota, Opt_offusrjquota, Opt_offgrpjquota,
Opt_jqfmt_vfsold, Opt_jqfmt_vfsv0, Opt_jqfmt_vfsv1, Opt_quota,
Opt_noquota, Opt_barrier, Opt_nobarrier, Opt_err,
- Opt_usrquota, Opt_grpquota, Opt_i_version,
+ Opt_usrquota, Opt_grpquota, Opt_i_version, Opt_dax,
Opt_stripe, Opt_delalloc, Opt_nodelalloc, Opt_mblk_io_submit,
Opt_nomblk_io_submit, Opt_block_validity, Opt_noblock_validity,
Opt_inode_readahead_blks, Opt_journal_ioprio,
@@ -1218,6 +1218,7 @@ static const match_table_t tokens = {
{Opt_barrier, "barrier"},
{Opt_nobarrier, "nobarrier"},
{Opt_i_version, "i_version"},
+ {Opt_dax, "dax"},
{Opt_stripe, "stripe=%u"},
{Opt_delalloc, "delalloc"},
{Opt_nodelalloc, "nodelalloc"},
@@ -1400,6 +1401,7 @@ static const struct mount_opts {
{Opt_min_batch_time, 0, MOPT_GTE0},
{Opt_inode_readahead_blks, 0, MOPT_GTE0},
{Opt_init_itable, 0, MOPT_GTE0},
+ {Opt_dax, EXT4_MOUNT_DAX, MOPT_SET},
{Opt_stripe, 0, MOPT_GTE0},
{Opt_resuid, 0, MOPT_GTE0},
{Opt_resgid, 0, MOPT_GTE0},
@@ -1638,6 +1640,11 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
}
sbi->s_jquota_fmt = m->mount_opt;
#endif
+#ifndef CONFIG_FS_DAX
+ } else if (token == Opt_dax) {
+ ext4_msg(sb, KERN_INFO, "dax option not supported");
+ return -1;
+#endif
} else {
if (!args->from)
arg = 1;
@@ -3560,6 +3567,11 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
"both data=journal and dioread_nolock");
goto failed_mount;
}
+ if (test_opt(sb, DAX)) {
+ ext4_msg(sb, KERN_ERR, "can't mount with "
+ "both data=journal and dax");
+ goto failed_mount;
+ }
if (test_opt(sb, DELALLOC))
clear_opt(sb, DELALLOC);
}
@@ -3613,6 +3625,19 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
goto failed_mount;
}

+ if (sbi->s_mount_opt & EXT4_MOUNT_DAX) {
+ if (blocksize != PAGE_SIZE) {
+ ext4_msg(sb, KERN_ERR,
+ "error: unsupported blocksize for dax");
+ goto failed_mount;
+ }
+ if (!sb->s_bdev->bd_disk->fops->direct_access) {
+ ext4_msg(sb, KERN_ERR,
+ "error: device does not support dax");
+ goto failed_mount;
+ }
+ }
+
if (sb->s_blocksize != blocksize) {
/* Validate the filesystem blocksize */
if (!sb_set_blocksize(sb, blocksize)) {
@@ -4813,6 +4838,18 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
err = -EINVAL;
goto restore_opts;
}
+ if (test_opt(sb, DAX)) {
+ ext4_msg(sb, KERN_ERR, "can't mount with "
+ "both data=journal and dax");
+ err = -EINVAL;
+ goto restore_opts;
+ }
+ }
+
+ if ((sbi->s_mount_opt ^ old_opts.s_mount_opt) & EXT4_MOUNT_DAX) {
+ ext4_msg(sb, KERN_WARNING, "warning: refusing change of "
+ "dax flag with busy inodes while remounting");
+ sbi->s_mount_opt ^= EXT4_MOUNT_DAX;
}

if (sbi->s_mount_flags & EXT4_MF_FS_ABORTED)
--
1.9.0


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