[PATCH v1] erofs: Fallback to normal access if DAX is not supported on extra device
Yuezhang Mo
Yuezhang.Mo at sony.com
Mon Jul 28 11:49:21 AEST 2025
If using multiple devices, we should check if the extra device support
DAX instead of checking the primary device when deciding if to use DAX
to access a file.
If an extra device does not support DAX we should fallback to normal
access otherwise the data on that device will be inaccessible.
Signed-off-by: Yuezhang Mo <Yuezhang.Mo at sony.com>
Reviewed-by: Friendy Su <friendy.su at sony.com>
Reviewed-by: Jacky Cao <jacky.cao at sony.com>
Reviewed-by: Daniel Palmer <daniel.palmer at sony.com>
---
fs/erofs/super.c | 23 ++++++++++++++---------
1 file changed, 14 insertions(+), 9 deletions(-)
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index e1020aa60771..ad1578bb0f7b 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -174,6 +174,11 @@ static int erofs_init_device(struct erofs_buf *buf, struct super_block *sb,
if (!erofs_is_fileio_mode(sbi)) {
dif->dax_dev = fs_dax_get_by_bdev(file_bdev(file),
&dif->dax_part_off, NULL, NULL);
+ if (!dif->dax_dev && test_opt(&sbi->opt, DAX_ALWAYS)) {
+ erofs_info(sb, "DAX unsupported by %s. Turning off DAX.",
+ dif->path);
+ clear_opt(&sbi->opt, DAX_ALWAYS);
+ }
} else if (!S_ISREG(file_inode(file)->i_mode)) {
fput(file);
return -EINVAL;
@@ -210,8 +215,13 @@ static int erofs_scan_devices(struct super_block *sb,
ondisk_extradevs, sbi->devs->extra_devices);
return -EINVAL;
}
- if (!ondisk_extradevs)
+ if (!ondisk_extradevs) {
+ if (test_opt(&sbi->opt, DAX_ALWAYS) && !sbi->dif0.dax_dev) {
+ erofs_info(sb, "DAX unsupported by block device. Turning off DAX.");
+ clear_opt(&sbi->opt, DAX_ALWAYS);
+ }
return 0;
+ }
if (!sbi->devs->extra_devices && !erofs_is_fscache_mode(sb))
sbi->devs->flatdev = true;
@@ -671,14 +681,9 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
return invalfc(fc, "cannot use fsoffset in fscache mode");
}
- if (test_opt(&sbi->opt, DAX_ALWAYS)) {
- if (!sbi->dif0.dax_dev) {
- errorfc(fc, "DAX unsupported by block device. Turning off DAX.");
- clear_opt(&sbi->opt, DAX_ALWAYS);
- } else if (sbi->blkszbits != PAGE_SHIFT) {
- errorfc(fc, "unsupported blocksize for DAX");
- clear_opt(&sbi->opt, DAX_ALWAYS);
- }
+ if (test_opt(&sbi->opt, DAX_ALWAYS) && sbi->blkszbits != PAGE_SHIFT) {
+ errorfc(fc, "unsupported blocksize for DAX");
+ clear_opt(&sbi->opt, DAX_ALWAYS);
}
sb->s_time_gran = 1;
--
2.43.0
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