[PATCH 04/11] fat: cleanup the flags for fat_truncate_time

Christoph Hellwig
2026-01-06T07:47:07Z

Fat only has a single on-disk timestamp covering ctime and mtime. Add
fat-specific flags that indicate which timestamp fat_truncate_time should
update to make this more clear. This allows removing no-op
fat_truncate_time calls with the S_CTIME flag and prepares for removing
the S_* flags.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/fat/dir.c | 2 +-
fs/fat/fat.h | 8 ++++----
fs/fat/file.c | 14 ++++++--------
fs/fat/inode.c | 2 +-
fs/fat/misc.c | 39 ++++++++++++++++-----------------------
fs/fat/namei_msdos.c | 13 +++++--------
fs/fat/namei_vfat.c | 9 ++++-----
7 files changed, 37 insertions(+), 50 deletions(-)

diff --git a/fs/fat/dir.c b/fs/fat/dir.c
index 92b091783966..3d03bff40944 100644
--- a/fs/fat/dir.c
+++ b/fs/fat/dir.c
@@ -1080,7 +1080,7 @@ int fat_remove_entries(struct inode *dir, struct fat_slot_info *sinfo)
}
}

- fat_truncate_time(dir, NULL, S_ATIME|S_MTIME);
+ fat_truncate_time(dir, NULL, FAT_UPDATE_ATIME | FAT_UPDATE_CMTIME);
if (IS_DIRSYNC(dir))
(void)fat_sync_inode(dir);
else
diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index d3e426de5f01..767b566b1cab 100644
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -468,10 +468,10 @@ extern void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
__le16 *time, __le16 *date, u8 *time_cs);
extern struct timespec64 fat_truncate_atime(const struct msdos_sb_info *sbi,
const struct timespec64 *ts);
-extern struct timespec64 fat_truncate_mtime(const struct msdos_sb_info *sbi,
- const struct timespec64 *ts);
-extern int fat_truncate_time(struct inode *inode, struct timespec64 *now,
- int flags);
+#define FAT_UPDATE_ATIME (1u << 0)
+#define FAT_UPDATE_CMTIME (1u << 1)
+void fat_truncate_time(struct inode *inode, struct timespec64 *now,
+ unsigned int flags);
extern int fat_update_time(struct inode *inode, int flags);
extern int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs);

diff --git a/fs/fat/file.c b/fs/fat/file.c
index 4fc49a614fb8..f9bc93411aa2 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -224,7 +224,7 @@ static int fat_cont_expand(struct inode *inode, loff_t size)
if (err)
goto out;

- fat_truncate_time(inode, NULL, S_CTIME|S_MTIME);
+ fat_truncate_time(inode, NULL, FAT_UPDATE_CMTIME);
mark_inode_dirty(inode);
if (IS_SYNC(inode)) {
int err2;
@@ -327,7 +327,7 @@ static int fat_free(struct inode *inode, int skip)
MSDOS_I(inode)->i_logstart = 0;
}
MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
- fat_truncate_time(inode, NULL, S_CTIME|S_MTIME);
+ fat_truncate_time(inode, NULL, FAT_UPDATE_CMTIME);
if (wait) {
err = fat_sync_inode(inode);
if (err) {
@@ -553,15 +553,13 @@ int fat_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
}

/*
- * setattr_copy can't truncate these appropriately, so we'll
- * copy them ourselves
+ * setattr_copy can't truncate these appropriately, so we'll copy them
+ * ourselves. See fat_truncate_time for the c/mtime logic on fat.
*/
if (attr->ia_valid & ATTR_ATIME)
- fat_truncate_time(inode, &attr->ia_atime, S_ATIME);
- if (attr->ia_valid & ATTR_CTIME)
- fat_truncate_time(inode, &attr->ia_ctime, S_CTIME);
+ fat_truncate_time(inode, &attr->ia_atime, FAT_UPDATE_ATIME);
if (attr->ia_valid & ATTR_MTIME)
- fat_truncate_time(inode, &attr->ia_mtime, S_MTIME);
+ fat_truncate_time(inode, &attr->ia_mtime, FAT_UPDATE_CMTIME);
attr->ia_valid &= ~(ATTR_ATIME|ATTR_CTIME|ATTR_MTIME);

setattr_copy(idmap, inode, attr);
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index 0b6009cd1844..59fa90617b5b 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -246,7 +246,7 @@ static int fat_write_end(const struct kiocb *iocb,
if (err < len)
fat_write_failed(mapping, pos + len);
if (!(err < 0) && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {
- fat_truncate_time(inode, NULL, S_CTIME|S_MTIME);
+ fat_truncate_time(inode, NULL, FAT_UPDATE_CMTIME);
MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
mark_inode_dirty(inode);
}
diff --git a/fs/fat/misc.c b/fs/fat/misc.c
index 950da09f0961..f4a1fa58bf05 100644
--- a/fs/fat/misc.c
+++ b/fs/fat/misc.c
@@ -299,43 +299,36 @@ struct timespec64 fat_truncate_atime(const struct msdos_sb_info *sbi,
}

/*
- * truncate mtime to 2 second granularity
- */
-struct timespec64 fat_truncate_mtime(const struct msdos_sb_info *sbi,
- const struct timespec64 *ts)
-{
- return fat_timespec64_trunc_2secs(*ts);
-}
-
-/*
- * truncate the various times with appropriate granularity:
- * all times in root node are always 0
+ * Update the in-inode atime and/or mtime after truncating the timestamp to the
+ * granularity. All timestamps in root inode are always 0.
+ *
+ * ctime and mtime share the same on-disk field, and should be identical in
+ * memory. All mtime updates will be applied to ctime, but ctime updates are
+ * ignored.
*/
-int fat_truncate_time(struct inode *inode, struct timespec64 *now, int flags)
+void fat_truncate_time(struct inode *inode, struct timespec64 *now,
+ unsigned int flags)
{
struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
struct timespec64 ts;

if (inode->i_ino == MSDOS_ROOT_INO)
- return 0;
+ return;

if (now == NULL) {
now = &ts;
ts = current_time(inode);
}

- if (flags & S_ATIME)
+ if (flags & FAT_UPDATE_ATIME)
inode_set_atime_to_ts(inode, fat_truncate_atime(sbi, now));
- /*
- * ctime and mtime share the same on-disk field, and should be
- * identical in memory. all mtime updates will be applied to ctime,
- * but ctime updates are ignored.
- */
- if (flags & S_MTIME)
- inode_set_mtime_to_ts(inode,
- inode_set_ctime_to_ts(inode, fat_truncate_mtime(sbi, now)));
+ if (flags & FAT_UPDATE_CMTIME) {
+ /* truncate mtime to 2 second granularity */
+ struct timespec64 mtime = fat_timespec64_trunc_2secs(*now);

- return 0;
+ inode_set_mtime_to_ts(inode, mtime);
+ inode_set_ctime_to_ts(inode, mtime);
+ }
}
EXPORT_SYMBOL_GPL(fat_truncate_time);

diff --git a/fs/fat/namei_msdos.c b/fs/fat/namei_msdos.c
index 0b920ee40a7f..ba0152ed0810 100644
--- a/fs/fat/namei_msdos.c
+++ b/fs/fat/namei_msdos.c
@@ -251,7 +251,7 @@ static int msdos_add_entry(struct inode *dir, const unsigned char *name,
if (err)
return err;

- fat_truncate_time(dir, ts, S_CTIME|S_MTIME);
+ fat_truncate_time(dir, ts, FAT_UPDATE_CMTIME);
if (IS_DIRSYNC(dir))
(void)fat_sync_inode(dir);
else
@@ -295,7 +295,7 @@ static int msdos_create(struct mnt_idmap *idmap, struct inode *dir,
err = PTR_ERR(inode);
goto out;
}
- fat_truncate_time(inode, &ts, S_ATIME|S_CTIME|S_MTIME);
+ fat_truncate_time(inode, &ts, FAT_UPDATE_ATIME | FAT_UPDATE_CMTIME);
/* timestamp is already written, so mark_inode_dirty() is unneeded. */

d_instantiate(dentry, inode);
@@ -328,7 +328,6 @@ static int msdos_rmdir(struct inode *dir, struct dentry *dentry)
drop_nlink(dir);

clear_nlink(inode);
- fat_truncate_time(inode, NULL, S_CTIME);
fat_detach(inode);
out:
mutex_unlock(&MSDOS_SB(sb)->s_lock);
@@ -382,7 +381,7 @@ static struct dentry *msdos_mkdir(struct mnt_idmap *idmap, struct inode *dir,
goto out;
}
set_nlink(inode, 2);
- fat_truncate_time(inode, &ts, S_ATIME|S_CTIME|S_MTIME);
+ fat_truncate_time(inode, &ts, FAT_UPDATE_ATIME | FAT_UPDATE_CMTIME);
/* timestamp is already written, so mark_inode_dirty() is unneeded. */

d_instantiate(dentry, inode);
@@ -415,7 +414,6 @@ static int msdos_unlink(struct inode *dir, struct dentry *dentry)
if (err)
goto out;
clear_nlink(inode);
- fat_truncate_time(inode, NULL, S_CTIME);
fat_detach(inode);
out:
mutex_unlock(&MSDOS_SB(sb)->s_lock);
@@ -480,7 +478,7 @@ static int do_msdos_rename(struct inode *old_dir, unsigned char *old_name,
mark_inode_dirty(old_inode);

inode_inc_iversion(old_dir);
- fat_truncate_time(old_dir, NULL, S_CTIME|S_MTIME);
+ fat_truncate_time(old_dir, NULL, FAT_UPDATE_CMTIME);
if (IS_DIRSYNC(old_dir))
(void)fat_sync_inode(old_dir);
else
@@ -540,7 +538,7 @@ static int do_msdos_rename(struct inode *old_dir, unsigned char *old_name,
if (err)
goto error_dotdot;
inode_inc_iversion(old_dir);
- fat_truncate_time(old_dir, &ts, S_CTIME|S_MTIME);
+ fat_truncate_time(old_dir, &ts, FAT_UPDATE_CMTIME);
if (IS_DIRSYNC(old_dir))
(void)fat_sync_inode(old_dir);
else
@@ -550,7 +548,6 @@ static int do_msdos_rename(struct inode *old_dir, unsigned char *old_name,
drop_nlink(new_inode);
if (is_dir)
drop_nlink(new_inode);
- fat_truncate_time(new_inode, &ts, S_CTIME);
}
out:
brelse(sinfo.bh);
diff --git a/fs/fat/namei_vfat.c b/fs/fat/namei_vfat.c
index 5dbc4cbb8fce..e46f34cade1a 100644
--- a/fs/fat/namei_vfat.c
+++ b/fs/fat/namei_vfat.c
@@ -676,7 +676,7 @@ static int vfat_add_entry(struct inode *dir, const struct qstr *qname,
goto cleanup;

/* update timestamp */
- fat_truncate_time(dir, ts, S_CTIME|S_MTIME);
+ fat_truncate_time(dir, ts, FAT_UPDATE_CMTIME);
if (IS_DIRSYNC(dir))
(void)fat_sync_inode(dir);
else
@@ -806,7 +806,7 @@ static int vfat_rmdir(struct inode *dir, struct dentry *dentry)
drop_nlink(dir);

clear_nlink(inode);
- fat_truncate_time(inode, NULL, S_ATIME|S_MTIME);
+ fat_truncate_time(inode, NULL, FAT_UPDATE_ATIME | FAT_UPDATE_CMTIME);
fat_detach(inode);
vfat_d_version_set(dentry, inode_query_iversion(dir));
out:
@@ -832,7 +832,7 @@ static int vfat_unlink(struct inode *dir, struct dentry *dentry)
if (err)
goto out;
clear_nlink(inode);
- fat_truncate_time(inode, NULL, S_ATIME|S_MTIME);
+ fat_truncate_time(inode, NULL, FAT_UPDATE_ATIME | FAT_UPDATE_CMTIME);
fat_detach(inode);
vfat_d_version_set(dentry, inode_query_iversion(dir));
out:
@@ -918,7 +918,7 @@ static int vfat_update_dotdot_de(struct inode *dir, struct inode *inode,
static void vfat_update_dir_metadata(struct inode *dir, struct timespec64 *ts)
{
inode_inc_iversion(dir);
- fat_truncate_time(dir, ts, S_CTIME | S_MTIME);
+ fat_truncate_time(dir, ts, FAT_UPDATE_CMTIME);
if (IS_DIRSYNC(dir))
(void)fat_sync_inode(dir);
else
@@ -996,7 +996,6 @@ static int vfat_rename(struct inode *old_dir, struct dentry *old_dentry,
drop_nlink(new_inode);
if (is_dir)
drop_nlink(new_inode);
- fat_truncate_time(new_inode, &ts, S_CTIME);
}
out:
brelse(sinfo.bh);