On 25/10/2024 04:45, Ritesh Harjani (IBM) wrote:
This patch adds base support for atomic writes via statx getattr.
On bs < ps systems, we can create FS with say bs of 16k. That means
both atomic write min and max unit can be set to 16k for supporting
atomic writes.
Later patches adds support for bigalloc as well so that ext4 can also
support doing atomic writes for bs = ps systems.
Co-developed-by: Ojaswin Mujoo <ojaswin@xxxxxxxxxxxxx>
Signed-off-by: Ojaswin Mujoo <ojaswin@xxxxxxxxxxxxx>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>
---
fs/ext4/ext4.h | 7 ++++++-
fs/ext4/inode.c | 14 ++++++++++++++
fs/ext4/super.c | 32 ++++++++++++++++++++++++++++++++
3 files changed, 52 insertions(+), 1 deletion(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 44b0d418143c..a41e56c2c628 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1729,6 +1729,10 @@ struct ext4_sb_info {
*/
struct work_struct s_sb_upd_work;
+ /* Atomic write unit values */
+ unsigned int fs_awu_min;
+ unsigned int fs_awu_max;
+
/* Ext4 fast commit sub transaction ID */
atomic_t s_fc_subtid;
@@ -1820,7 +1824,8 @@ static inline int ext4_valid_inum(struct super_block *sb, unsigned long ino)
*/
enum {
EXT4_MF_MNTDIR_SAMPLED,
- EXT4_MF_FC_INELIGIBLE /* Fast commit ineligible */
+ EXT4_MF_FC_INELIGIBLE, /* Fast commit ineligible */
+ EXT4_MF_ATOMIC_WRITE /* Supports atomic write */
Does this flag really buy us much?
};
static inline void ext4_set_mount_flag(struct super_block *sb, int bit)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 54bdd4884fe6..897c028d5bc9 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5578,6 +5578,20 @@ int ext4_getattr(struct mnt_idmap *idmap, const struct path *path,
}
}
+ if (S_ISREG(inode->i_mode) && (request_mask & STATX_WRITE_ATOMIC)) {
+ struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+ unsigned int awu_min, awu_max;
+
+ if (ext4_test_mount_flag(inode->i_sb, EXT4_MF_ATOMIC_WRITE)) {
I'd use ext4_inode_can_atomicwrite() here, similar to what is done for xfs
+ awu_min = sbi->fs_awu_min;
+ awu_max = sbi->fs_awu_max;
+ } else {
+ awu_min = awu_max = 0;
+ }
+
+ generic_fill_statx_atomic_writes(stat, awu_min, awu_max);
+ }
+
flags = ei->i_flags & EXT4_FL_USER_VISIBLE;
if (flags & EXT4_APPEND_FL)
stat->attributes |= STATX_ATTR_APPEND;
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 16a4ce704460..f5c075aff060 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4425,6 +4425,37 @@ static int ext4_handle_clustersize(struct super_block *sb)
return 0;
}
+/*
