Linux EXT4 FS development
 help / color / mirror / Atom feed
* [PATCH v4] ext2: Remove deprecated DAX support
@ 2026-05-24 15:35 Ashwin Gundarapu
  2026-05-28  4:16 ` kernel test robot
  0 siblings, 1 reply; 4+ messages in thread
From: Ashwin Gundarapu @ 2026-05-24 15:35 UTC (permalink / raw)
  To: jack; +Cc: linux-ext4, linux-kernel

DAX support in ext2 was deprecated in commit d5a2693f93e4
("ext2: Deprecate DAX") with a removal deadline of end of 2025.
Remove all DAX code from ext2 as scheduled.

This removes the DAX mount option, IOMAP DAX support, DAX file
operations, DAX address_space_operations, and the DAX fault handler.

Signed-off-by: Ashwin Gundarapu <linuxuser509@zohomail.in>
---
v4: Changed Opt_xip and Opt_dax from -EINVAL to warning with break
    to avoid mount failures. Removed dead XIP/DAX show_options code.
v3: Restored Opt_dax for graceful mount error message. Fixed remaining
    space-to-tab indentation. Kept EXT2_MOUNT_XIP for compilation.
v2: Removed unused sbi variable and fixed indentation as reported
    by kernel test robot.
---
 fs/ext2/ext2.h  |   5 +-
 fs/ext2/file.c  | 118 ++----------------------------------------------
 fs/ext2/inode.c |  61 ++-----------------------
 fs/ext2/super.c |  47 ++++---------------
 4 files changed, 18 insertions(+), 213 deletions(-)

diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
index 3eb1f342645c..3a26308ec841 100644
--- a/fs/ext2/ext2.h
+++ b/fs/ext2/ext2.h
@@ -114,8 +114,6 @@ struct ext2_sb_info {
 	 */
 	spinlock_t s_lock;
 	struct mb_cache *s_ea_block_cache;
-	struct dax_device *s_daxdev;
-	u64 s_dax_part_off;
 };
 
 static inline spinlock_t *
@@ -373,11 +371,10 @@ struct ext2_inode {
 #define EXT2_MOUNT_NO_UID32		0x000200  /* Disable 32-bit UIDs */
 #define EXT2_MOUNT_XATTR_USER		0x004000  /* Extended user attributes */
 #define EXT2_MOUNT_POSIX_ACL		0x008000  /* POSIX Access Control Lists */
-#define EXT2_MOUNT_XIP			0x010000  /* Obsolete, use DAX */
+#define EXT2_MOUNT_XIP			0x010000  /* Obsolete*/
 #define EXT2_MOUNT_USRQUOTA		0x020000  /* user quota */
 #define EXT2_MOUNT_GRPQUOTA		0x040000  /* group quota */
 #define EXT2_MOUNT_RESERVATION		0x080000  /* Preallocation */
-#define EXT2_MOUNT_DAX			0x100000  /* Direct Access */
 
 
 #define clear_opt(o, opt)		o &= ~EXT2_MOUNT_##opt
diff --git a/fs/ext2/file.c b/fs/ext2/file.c
index d9b1eb34694a..0fd9208af062 100644
--- a/fs/ext2/file.c
+++ b/fs/ext2/file.c
@@ -21,7 +21,6 @@
 
 #include <linux/time.h>
 #include <linux/pagemap.h>
-#include <linux/dax.h>
 #include <linux/filelock.h>
 #include <linux/quotaops.h>
 #include <linux/iomap.h>
@@ -32,111 +31,6 @@
 #include "acl.h"
 #include "trace.h"

-#ifdef CONFIG_FS_DAX
-static ssize_t ext2_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
-{
-	struct inode *inode = iocb->ki_filp->f_mapping->host;
-	ssize_t ret;
-
-	if (!iov_iter_count(to))
-		return 0; /* skip atime */
-
-	inode_lock_shared(inode);
-	ret = dax_iomap_rw(iocb, to, &ext2_iomap_ops);
-	inode_unlock_shared(inode);
-
-	file_accessed(iocb->ki_filp);
-	return ret;
-}
-
-static ssize_t ext2_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
-{
-	struct file *file = iocb->ki_filp;
-	struct inode *inode = file->f_mapping->host;
-	ssize_t ret;
-
-	inode_lock(inode);
-	ret = generic_write_checks(iocb, from);
-	if (ret <= 0)
-		goto out_unlock;
-	ret = file_remove_privs(file);
-	if (ret)
-		goto out_unlock;
-	ret = file_update_time(file);
-	if (ret)
-		goto out_unlock;
-
-	ret = dax_iomap_rw(iocb, from, &ext2_iomap_ops);
-	if (ret > 0 && iocb->ki_pos > i_size_read(inode)) {
-		i_size_write(inode, iocb->ki_pos);
-		mark_inode_dirty(inode);
-	}
-
-out_unlock:
-	inode_unlock(inode);
-	if (ret > 0)
-		ret = generic_write_sync(iocb, ret);
-	return ret;
-}
-
-/*
- * The lock ordering for ext2 DAX fault paths is:
- *
- * mmap_lock (MM)
- *   sb_start_pagefault (vfs, freeze)
- *     address_space->invalidate_lock
- *       address_space->i_mmap_rwsem or page_lock (mutually exclusive in DAX)
- *         ext2_inode_info->truncate_mutex
- *
- * The default page_lock and i_size verification done by non-DAX fault paths
- * is sufficient because ext2 doesn't support hole punching.
- */
-static vm_fault_t ext2_dax_fault(struct vm_fault *vmf)
-{
-	struct inode *inode = file_inode(vmf->vma->vm_file);
-	vm_fault_t ret;
-	bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
-		(vmf->vma->vm_flags & VM_SHARED);
-
-	if (write) {
-		sb_start_pagefault(inode->i_sb);
-		file_update_time(vmf->vma->vm_file);
-	}
-	filemap_invalidate_lock_shared(inode->i_mapping);
-
-	ret = dax_iomap_fault(vmf, 0, NULL, NULL, &ext2_iomap_ops);
-
-	filemap_invalidate_unlock_shared(inode->i_mapping);
-	if (write)
-		sb_end_pagefault(inode->i_sb);
-	return ret;
-}
-
-static const struct vm_operations_struct ext2_dax_vm_ops = {
-	.fault		= ext2_dax_fault,
-	/*
-	 * .huge_fault is not supported for DAX because allocation in ext2
-	 * cannot be reliably aligned to huge page sizes and so pmd faults
-	 * will always fail and fail back to regular faults.
-	 */
-	.page_mkwrite	= ext2_dax_fault,
-	.pfn_mkwrite	= ext2_dax_fault,
-};
-
-static int ext2_file_mmap_prepare(struct vm_area_desc *desc)
-{
-	struct file *file = desc->file;
-
-	if (!IS_DAX(file_inode(file)))
-		return generic_file_mmap_prepare(desc);
-
-	file_accessed(file);
-	desc->vm_ops = &ext2_dax_vm_ops;
-	return 0;
-}
-#else
-#define ext2_file_mmap_prepare	generic_file_mmap_prepare
-#endif
 
 /*
  * Called when filp is released. This happens when all file descriptors
@@ -285,10 +179,7 @@ static ssize_t ext2_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
 
 static ssize_t ext2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
-#ifdef CONFIG_FS_DAX
-	if (IS_DAX(iocb->ki_filp->f_mapping->host))
-		return ext2_dax_read_iter(iocb, to);
-#endif
+
 	if (iocb->ki_flags & IOCB_DIRECT)
 		return ext2_dio_read_iter(iocb, to);
 
@@ -297,10 +188,7 @@ static ssize_t ext2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)

 static ssize_t ext2_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
-#ifdef CONFIG_FS_DAX
-	if (IS_DAX(iocb->ki_filp->f_mapping->host))
-		return ext2_dax_write_iter(iocb, from);
-#endif
+
 	if (iocb->ki_flags & IOCB_DIRECT)
 		return ext2_dio_write_iter(iocb, from);
 
@@ -321,7 +209,7 @@ const struct file_operations ext2_file_operations = {
 #ifdef CONFIG_COMPAT
 	.compat_ioctl	= ext2_compat_ioctl,
 #endif
-	.mmap_prepare	= ext2_file_mmap_prepare,
+	.mmap_prepare = generic_file_mmap_prepare,
 	.open		= ext2_file_open,
 	.release	= ext2_release_file,
 	.fsync		= ext2_fsync,
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 74aca5eb572d..e2aa6152fa1f 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -26,7 +26,6 @@
 #include <linux/time.h>
 #include <linux/highuid.h>
 #include <linux/pagemap.h>
-#include <linux/dax.h>
 #include <linux/blkdev.h>
 #include <linux/quotaops.h>
 #include <linux/writeback.h>
@@ -741,27 +740,6 @@ static int ext2_get_blocks(struct inode *inode,
 		goto cleanup;
 	}
 
-	if (IS_DAX(inode)) {
-		/*
-		 * We must unmap blocks before zeroing so that writeback cannot
-		 * overwrite zeros with stale data from block device page cache.
-		 */
-		clean_bdev_aliases(inode->i_sb->s_bdev,
-				   le32_to_cpu(chain[depth-1].key),
-				   count);
-		/*
-		 * block must be initialised before we put it in the tree
-		 * so that it's not found by another thread before it's
-		 * initialised
-		 */
-		err = sb_issue_zeroout(inode->i_sb,
-				le32_to_cpu(chain[depth-1].key), count,
-				GFP_KERNEL);
-		if (err) {
-			mutex_unlock(&ei->truncate_mutex);
-			goto cleanup;
-		}
-	}
 	*new = true;

 	ext2_splice_branch(inode, iblock, partial, indirect_blks, count);
@@ -811,7 +789,6 @@ static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 	unsigned int blkbits = inode->i_blkbits;
 	unsigned long first_block = offset >> blkbits;
 	unsigned long max_blocks = (length + (1 << blkbits) - 1) >> blkbits;
-	struct ext2_sb_info *sbi = EXT2_SB(inode->i_sb);
 	bool new = false, boundary = false;
 	u32 bno;
 	int ret;
@@ -841,10 +818,7 @@ static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 
 	iomap->flags = 0;
 	iomap->offset = (u64)first_block << blkbits;
-	if (flags & IOMAP_DAX)
-		iomap->dax_dev = sbi->s_daxdev;
-	else
-		iomap->bdev = inode->i_sb->s_bdev;
+	iomap->bdev = inode->i_sb->s_bdev;
 
 	if (ret == 0) {
 		/*
@@ -859,8 +833,6 @@ static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
 	} else {
 		iomap->type = IOMAP_MAPPED;
 		iomap->addr = (u64)bno << blkbits;
-		if (flags & IOMAP_DAX)
-			iomap->addr += sbi->s_dax_part_off;
 		iomap->length = (u64)ret << blkbits;
 		iomap->flags |= IOMAP_F_MERGED;
 	}
@@ -962,13 +934,6 @@ ext2_writepages(struct address_space *mapping, struct writeback_control *wbc)
 	return mpage_writepages(mapping, wbc, ext2_get_block);
 }

-static int
-ext2_dax_writepages(struct address_space *mapping, struct writeback_control *wbc)
-{
-	struct ext2_sb_info *sbi = EXT2_SB(mapping->host->i_sb);
-
-	return dax_writeback_mapping_range(mapping, sbi->s_daxdev, wbc);
-}
 
 const struct address_space_operations ext2_aops = {
 	.dirty_folio		= block_dirty_folio,
@@ -984,10 +949,6 @@ const struct address_space_operations ext2_aops = {
 	.error_remove_folio	= generic_error_remove_folio,
 };
 
-static const struct address_space_operations ext2_dax_aops = {
-	.writepages		= ext2_dax_writepages,
-	.dirty_folio		= noop_dirty_folio,
-};

 /*
  * Probably it should be a library function... search for first non-zero word
@@ -1186,9 +1147,6 @@ static void __ext2_truncate_blocks(struct inode *inode, loff_t offset)
 	blocksize = inode->i_sb->s_blocksize;
 	iblock = (offset + blocksize-1) >> EXT2_BLOCK_SIZE_BITS(inode->i_sb);
 
-#ifdef CONFIG_FS_DAX
-	WARN_ON(!rwsem_is_locked(&inode->i_mapping->invalidate_lock));
-#endif
 
 	n = ext2_block_to_path(inode, iblock, offsets, NULL);
 	if (n == 0)
@@ -1290,12 +1248,8 @@ static int ext2_setsize(struct inode *inode, loff_t newsize)
 
 	inode_dio_wait(inode);
 
-	if (IS_DAX(inode))
-		error = dax_truncate_page(inode, newsize, NULL,
-					  &ext2_iomap_ops);
-	else
-		error = block_truncate_page(inode->i_mapping,
-				newsize, ext2_get_block);
+			error = block_truncate_page(inode->i_mapping,
+								newsize, ext2_get_block);
 	if (error)
 		return error;
 
@@ -1363,7 +1317,7 @@ void ext2_set_inode_flags(struct inode *inode)
 	unsigned int flags = EXT2_I(inode)->i_flags;

 	inode->i_flags &= ~(S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME |
-				S_DIRSYNC | S_DAX);
+				S_DIRSYNC);
 	if (flags & EXT2_SYNC_FL)
 		inode->i_flags |= S_SYNC;
 	if (flags & EXT2_APPEND_FL)
@@ -1374,18 +1328,13 @@ void ext2_set_inode_flags(struct inode *inode)
 		inode->i_flags |= S_NOATIME;
 	if (flags & EXT2_DIRSYNC_FL)
 		inode->i_flags |= S_DIRSYNC;
-	if (test_opt(inode->i_sb, DAX) && S_ISREG(inode->i_mode))
-		inode->i_flags |= S_DAX;
 }
 
 void ext2_set_file_ops(struct inode *inode)
 {
 	inode->i_op = &ext2_file_inode_operations;
 	inode->i_fop = &ext2_file_operations;
-	if (IS_DAX(inode))
-		inode->i_mapping->a_ops = &ext2_dax_aops;
-	else
-		inode->i_mapping->a_ops = &ext2_aops;
+	inode->i_mapping->a_ops = &ext2_aops;
 }
 
 struct inode *ext2_iget (struct super_block *sb, unsigned long ino)
diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index 19f76d8cb473..39f67f1d63cc 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -34,7 +34,6 @@
 #include <linux/log2.h>
 #include <linux/quotaops.h>
 #include <linux/uaccess.h>
-#include <linux/dax.h>
 #include <linux/iversion.h>
 #include "ext2.h"
 #include "xattr.h"
@@ -198,7 +197,6 @@ static void ext2_put_super (struct super_block * sb)
 	brelse (sbi->s_sbh);
 	sb->s_fs_info = NULL;
 	kfree(sbi->s_blockgroup_lock);
-	fs_put_dax(sbi->s_daxdev, NULL);
 	kfree(sbi);
 }
 
@@ -329,11 +327,7 @@ static int ext2_show_options(struct seq_file *seq, struct dentry *root)
 	if (test_opt(sb, GRPQUOTA))
 		seq_puts(seq, ",grpquota");
 
-	if (test_opt(sb, XIP))
-		seq_puts(seq, ",xip");
 
-	if (test_opt(sb, DAX))
-		seq_puts(seq, ",dax");

 	if (!test_opt(sb, RESERVATION))
 		seq_puts(seq, ",noreservation");
@@ -595,20 +589,12 @@ static int ext2_parse_param(struct fs_context *fc, struct fs_parameter *param)
 		ext2_msg_fc(fc, KERN_INFO, "(no)acl options not supported");
 		break;
 #endif
-	case Opt_xip:
-		ext2_msg_fc(fc, KERN_INFO, "use dax instead of xip");
-		ctx_set_mount_opt(ctx, EXT2_MOUNT_XIP);
-		fallthrough;
-	case Opt_dax:
-#ifdef CONFIG_FS_DAX
-		ext2_msg_fc(fc, KERN_WARNING,
-		    "DAX enabled. Warning: DAX support in ext2 driver is deprecated"
-		    " and will be removed at the end of 2025. Please use ext4 driver instead.");
-		ctx_set_mount_opt(ctx, EXT2_MOUNT_DAX);
-#else
-		ext2_msg_fc(fc, KERN_INFO, "dax option not supported");
-#endif
-		break;
+		case Opt_xip:
+				ext2_msg_fc(fc, KERN_WARNING, "DAX support has been removed. xip option ignored.");
+				break;
+		case Opt_dax:
+			ext2_msg_fc(fc, KERN_WARNING, "DAX support has been removed. dax option ignored.");
+			break;
 
 #if defined(CONFIG_QUOTA)
 	case Opt_quota:
@@ -906,8 +892,6 @@ static int ext2_fill_super(struct super_block *sb, struct fs_context *fc)
 	}
 	sb->s_fs_info = sbi;
 	sbi->s_sb_block = sb_block;
-	sbi->s_daxdev = fs_dax_get_by_bdev(sb->s_bdev, &sbi->s_dax_part_off,
-					   NULL, NULL);

 	spin_lock_init(&sbi->s_lock);
 	ret = -EINVAL;
@@ -992,16 +976,8 @@ static int ext2_fill_super(struct super_block *sb, struct fs_context *fc)
 	}
 	blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);

-	if (test_opt(sb, DAX)) {
-		if (!sbi->s_daxdev) {
-			ext2_msg(sb, KERN_ERR,
-				"DAX unsupported by block device. Turning off DAX.");
-			clear_opt(sbi->s_mount_opt, DAX);
-		} else if (blocksize != PAGE_SIZE) {
-			ext2_msg(sb, KERN_ERR, "unsupported blocksize for DAX\n");
-			clear_opt(sbi->s_mount_opt, DAX);
-		}
-	}
+
+

 	/* If the blocksize doesn't match, re-read the thing.. */
 	if (sb->s_blocksize != blocksize) {
@@ -1252,7 +1228,6 @@ static int ext2_fill_super(struct super_block *sb, struct fs_context *fc)
 failed_mount:
 	brelse(bh);
 failed_sbi:
-	fs_put_dax(sbi->s_daxdev, NULL);
 	sb->s_fs_info = NULL;
 	kfree(sbi->s_blockgroup_lock);
 	kfree(sbi);
@@ -1379,11 +1354,7 @@ static int ext2_reconfigure(struct fs_context *fc)

 	spin_lock(&sbi->s_lock);
 	es = sbi->s_es;
-	if ((sbi->s_mount_opt ^ new_opts.s_mount_opt) & EXT2_MOUNT_DAX) {
-		ext2_msg(sb, KERN_WARNING, "warning: refusing change of "
-			 "dax flag with busy inodes while remounting");
-		new_opts.s_mount_opt ^= EXT2_MOUNT_DAX;
-	}
+
 	if ((bool)(flags & SB_RDONLY) == sb_rdonly(sb))
 		goto out_set;
 	if (flags & SB_RDONLY) {
--
2.43.0



^ permalink raw reply related	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2026-06-01  9:29 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-05-24 15:35 [PATCH v4] ext2: Remove deprecated DAX support Ashwin Gundarapu
2026-05-28  4:16 ` kernel test robot
2026-05-28  8:26   ` Ashwin Gundarapu
2026-06-01  9:29     ` Jan Kara

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox