fs/ext4: Update ext4_should_use_dax()

S_DAX should only be enabled when the underlying block device supports
dax.

Cache the underlying support for DAX in the super block and modify
ext4_should_use_dax() to check for device support prior to the over
riding mount option.

While we are at it change the function to ext4_should_enable_dax() as
this better reflects the ask as well as matches xfs.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Link: https://lore.kernel.org/r/20200528150003.828793-5-ira.weiny@intel.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 1a3daf2d18ef7f0babc69a5c92bd2bb01345f2cb..0b4db9ce775663a2791af0f9f1c12633f8694411 100644 (file)
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1979,6 +1979,7 @@ static inline bool ext4_has_incompat_features(struct super_block *sb)
  */
 #define EXT4_FLAGS_RESIZING    0
 #define EXT4_FLAGS_SHUTDOWN    1
+#define EXT4_FLAGS_BDEV_IS_DAX 2
 
 static inline int ext4_forced_shutdown(struct ext4_sb_info *sbi)
 {

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index a10ff12194dbcc59de3db38b374ab4f4d98a1b6a..6532870f6a0bc3b12e25a86b2e9414ba93c68da3 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4398,10 +4398,10 @@ int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc)
                !ext4_test_inode_state(inode, EXT4_STATE_XATTR));
 }
 
-static bool ext4_should_use_dax(struct inode *inode)
+static bool ext4_should_enable_dax(struct inode *inode)
 {
-       if (!test_opt(inode->i_sb, DAX_ALWAYS))
-               return false;
+       struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+
        if (!S_ISREG(inode->i_mode))
                return false;
        if (ext4_should_journal_data(inode))
@@ -4412,7 +4412,12 @@ static bool ext4_should_use_dax(struct inode *inode)
                return false;
        if (ext4_test_inode_flag(inode, EXT4_INODE_VERITY))
                return false;
-       return true;
+       if (!test_bit(EXT4_FLAGS_BDEV_IS_DAX, &sbi->s_ext4_flags))
+               return false;
+       if (test_opt(inode->i_sb, DAX_ALWAYS))
+               return true;
+
+       return false;
 }
 
 void ext4_set_inode_flags(struct inode *inode)
@@ -4430,7 +4435,7 @@ void ext4_set_inode_flags(struct inode *inode)
                new_fl |= S_NOATIME;
        if (flags & EXT4_DIRSYNC_FL)
                new_fl |= S_DIRSYNC;
-       if (ext4_should_use_dax(inode))
+       if (ext4_should_enable_dax(inode))
                new_fl |= S_DAX;
        if (flags & EXT4_ENCRYPT_FL)
                new_fl |= S_ENCRYPTED;

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 7b99c44d0a9186e07b5ea032928b2d8856bc2794..f7d76dcaedfee683c41c33af12d930b84477cb09 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4092,13 +4092,16 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
                goto failed_mount;
        }
 
+       if (bdev_dax_supported(sb->s_bdev, blocksize))
+               set_bit(EXT4_FLAGS_BDEV_IS_DAX, &sbi->s_ext4_flags);
+
        if (sbi->s_mount_opt & EXT4_MOUNT_DAX_ALWAYS) {
                if (ext4_has_feature_inline_data(sb)) {
                        ext4_msg(sb, KERN_ERR, "Cannot use DAX on a filesystem"
                                        " that may contain inline data");
                        goto failed_mount;
                }
-               if (!bdev_dax_supported(sb->s_bdev, blocksize)) {
+               if (!test_bit(EXT4_FLAGS_BDEV_IS_DAX, &sbi->s_ext4_flags)) {
                        ext4_msg(sb, KERN_ERR,
                                "DAX unsupported by block device.");
                        goto failed_mount;