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ext4: Add statx support for atomic writes

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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.

Co-developed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Ritesh Harjani (IBM) 2024-11-04 16:22:57 -08:00 committed by Darrick J. Wong
parent 3af5298ce9
commit 6dfc1c1d59
3 changed files with 53 additions and 0 deletions
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10
fs/ext4/ext4.h
View File

@ -1729,6 +1729,10 @@ struct ext4_sb_info {
*/
struct work_struct s_sb_upd_work;
/* Atomic write unit values in bytes */
unsigned int s_awu_min;
unsigned int s_awu_max;
/* Ext4 fast commit sub transaction ID */
atomic_t s_fc_subtid;
@ -3855,6 +3859,12 @@ static inline int ext4_buffer_uptodate(struct buffer_head *bh)
return buffer_uptodate(bh);
}
static inline bool ext4_inode_can_atomic_write(struct inode *inode)
{
return S_ISREG(inode->i_mode) && EXT4_SB(inode->i_sb)->s_awu_min > 0;
}
extern int ext4_block_write_begin(handle_t *handle, struct folio *folio,
loff_t pos, unsigned len,
get_block_t *get_block);

12
fs/ext4/inode.c
View File

@ -5578,6 +5578,18 @@ int ext4_getattr(struct mnt_idmap *idmap, const struct path *path,
}
}
if ((request_mask & STATX_WRITE_ATOMIC) && S_ISREG(inode->i_mode)) {
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
unsigned int awu_min = 0, awu_max = 0;
if (ext4_inode_can_atomic_write(inode)) {
awu_min = sbi->s_awu_min;
awu_max = sbi->s_awu_max;
}
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;

31
fs/ext4/super.c
View File

@ -4425,6 +4425,36 @@ static int ext4_handle_clustersize(struct super_block *sb)
return 0;
}
/*
* ext4_atomic_write_init: Initializes filesystem min & max atomic write units.
* @sb: super block
* TODO: Later add support for bigalloc
*/
static void ext4_atomic_write_init(struct super_block *sb)
{
struct ext4_sb_info *sbi = EXT4_SB(sb);
struct block_device *bdev = sb->s_bdev;
if (!bdev_can_atomic_write(bdev))
return;
if (!ext4_has_feature_extents(sb))
return;
sbi->s_awu_min = max(sb->s_blocksize,
bdev_atomic_write_unit_min_bytes(bdev));
sbi->s_awu_max = min(sb->s_blocksize,
bdev_atomic_write_unit_max_bytes(bdev));
if (sbi->s_awu_min && sbi->s_awu_max &&
sbi->s_awu_min <= sbi->s_awu_max) {
ext4_msg(sb, KERN_NOTICE, "Supports (experimental) DIO atomic writes awu_min: %u, awu_max: %u",
sbi->s_awu_min, sbi->s_awu_max);
} else {
sbi->s_awu_min = 0;
sbi->s_awu_max = 0;
}
}
static void ext4_fast_commit_init(struct super_block *sb)
{
struct ext4_sb_info *sbi = EXT4_SB(sb);
@ -5336,6 +5366,7 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
spin_lock_init(&sbi->s_bdev_wb_lock);
ext4_atomic_write_init(sb);
ext4_fast_commit_init(sb);
sb->s_root = NULL;