[PATCH V4 0/4] fat: timestamp updates

[PATCH V4 0/4] fat: timestamp updates

[Frank Sorenson]

fat/msdos timestamps are stored on-disk with several different
granularities, some of them lower resolution than timespec64_trunc()
can provide.  In addition, they are only truncated as they are
written to disk, so the timestamps in-memory for new or modified
files/directories may be different from the same timestamps after
a remount, as the now-truncated times are re-read from the on-disk
format.

These patches allow finer granularity for the timestamps where
possible and add fat-specific ->update_time inode operation and
fat_truncate_time functions to truncate each timestamp correctly,
giving consistent times across remounts.


V4 changes
  corrected to use fat_truncate_time() and keep mark_inode_dirty()
  set s_time_gran to 1ns unconditionally
  add i_version support to update_time()
  fix atime bug with localtime


Frank Sorenson (4):
  fat: create a function to calculate the timezone offest
  fat: add functions to update and truncate timestamps appropriately
  fat: change timestamp updates to use fat_truncate_time
  fat: truncate inode timestamp updates in setattr

 fs/fat/dir.c         |  2 +-
 fs/fat/fat.h         |  2 ++
 fs/fat/file.c        | 17 ++++++++--
 fs/fat/inode.c       |  9 ++++--
 fs/fat/misc.c        | 91 ++++++++++++++++++++++++++++++++++++++++++++++++----
 fs/fat/namei_msdos.c | 17 +++++-----
 fs/fat/namei_vfat.c  | 15 +++++----
 7 files changed, 126 insertions(+), 27 deletions(-)

-- 
2.14.4

[PATCH V4 1/4] fat: create a function to calculate the timezone offest

[Frank Sorenson]

Move the calculation of the number of seconds in the timezone
offset to a common function.

Signed-off-by: Frank Sorenson <sorenson@redhat.com>
---
 fs/fat/misc.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/fs/fat/misc.c b/fs/fat/misc.c
index 573836dcaefc..2eca073fe785 100644
--- a/fs/fat/misc.c
+++ b/fs/fat/misc.c
@@ -185,6 +185,13 @@ static long days_in_year[] = {
 	0,   0,  31,  59,  90, 120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0,
 };
 
+static inline int fat_tz_offset(struct msdos_sb_info *sbi)
+{
+	return (sbi->options.tz_set ?
+	       -sbi->options.time_offset :
+	       sys_tz.tz_minuteswest) * SECS_PER_MIN;
+}
+
 /* Convert a FAT time/date pair to a UNIX date (seconds since 1 1 70). */
 void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec64 *ts,
 		       __le16 __time, __le16 __date, u8 time_cs)
@@ -210,10 +217,7 @@ void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec64 *ts,
 		   + days_in_year[month] + day
 		   + DAYS_DELTA) * SECS_PER_DAY;
 
-	if (!sbi->options.tz_set)
-		second += sys_tz.tz_minuteswest * SECS_PER_MIN;
-	else
-		second -= sbi->options.time_offset * SECS_PER_MIN;
+	second += fat_tz_offset(sbi);
 
 	if (time_cs) {
 		ts->tv_sec = second + (time_cs / 100);
@@ -229,9 +233,7 @@ void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
 		       __le16 *time, __le16 *date, u8 *time_cs)
 {
 	struct tm tm;
-	time64_to_tm(ts->tv_sec,
-		   (sbi->options.tz_set ? sbi->options.time_offset :
-		   -sys_tz.tz_minuteswest) * SECS_PER_MIN, &tm);
+	time64_to_tm(ts->tv_sec, -fat_tz_offset(sbi), &tm);
 
 	/*  FAT can only support year between 1980 to 2107 */
 	if (tm.tm_year < 1980 - 1900) {
-- 
2.14.4

[PATCH V2 2/4] fat: add functions to update and truncate timestamps appropriately

[Frank Sorenson]

Add the fat-specific inode_operation ->update_time() and
fat_truncate_time() function to truncate the inode timestamps
from 1 nanosecond to the appropriate granularity.

Signed-off-by: Frank Sorenson <sorenson@redhat.com>
---
 fs/fat/fat.h         |  2 ++
 fs/fat/file.c        |  1 +
 fs/fat/inode.c       |  5 ++++
 fs/fat/misc.c        | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/fat/namei_msdos.c |  1 +
 fs/fat/namei_vfat.c  |  1 +
 6 files changed, 85 insertions(+)

diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index 9d7d2d5da28b..3976a2fc787a 100644
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -416,6 +416,8 @@ extern void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec64 *ts,
 			      __le16 __time, __le16 __date, u8 time_cs);
 extern void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
 			      __le16 *time, __le16 *date, u8 *time_cs);
+extern int fat_truncate_time(struct inode *inode, struct timespec64 *now, int flags);
+extern int fat_update_time(struct inode *inode, struct timespec64 *now, int flags);
 extern int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs);
 
 int fat_cache_init(void);
diff --git a/fs/fat/file.c b/fs/fat/file.c
index 4f3d72fb1e60..19b6b0566411 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -552,4 +552,5 @@ EXPORT_SYMBOL_GPL(fat_setattr);
 const struct inode_operations fat_file_inode_operations = {
 	.setattr	= fat_setattr,
 	.getattr	= fat_getattr,
+	.update_time	= fat_update_time,
 };
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index d6b81e31f9f5..3bf60f19b6d3 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -1626,6 +1626,11 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
 	sb->s_magic = MSDOS_SUPER_MAGIC;
 	sb->s_op = &fat_sops;
 	sb->s_export_op = &fat_export_ops;
+	/*
+	 * fat timestamps are complex and truncated by fat itself, so
+	 * we set 1 here to be fast
+	 */
+	sb->s_time_gran = 1;
 	mutex_init(&sbi->nfs_build_inode_lock);
 	ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
 			     DEFAULT_RATELIMIT_BURST);
diff --git a/fs/fat/misc.c b/fs/fat/misc.c
index 2eca073fe785..7eb2a756333f 100644
--- a/fs/fat/misc.c
+++ b/fs/fat/misc.c
@@ -7,6 +7,7 @@
  */
 
 #include "fat.h"
+#include <linux/iversion.h>
 
 /*
  * fat_fs_error reports a file system problem that might indicate fa data
@@ -265,6 +266,80 @@ void fat_time_unix2fat(struct msdos_sb_info *sbi, struct timespec64 *ts,
 }
 EXPORT_SYMBOL_GPL(fat_time_unix2fat);
 
+static inline struct timespec64 fat_timespec64_trunc_2secs(struct timespec64 ts)
+{
+	return (struct timespec64){ ts.tv_sec & ~1ULL, 0 };
+}
+/*
+ * truncate the various times with appropriate granularity:
+ *   root inode:
+ *     all times always 0
+ *   all other inodes:
+ *     mtime - 2 seconds
+ *     ctime
+ *       msdos - 2 seconds
+ *       vfat  - 10 milliseconds
+ *     atime - 24 hours (00:00:00 in local timezone)
+ */
+int fat_truncate_time(struct inode *inode, struct timespec64 *now, int flags)
+{
+	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
+	struct timespec64 ts;
+
+	if (inode->i_ino == MSDOS_ROOT_INO)
+	return 0;
+
+	if (now == NULL) {
+		now = &ts;
+		ts = current_time(inode);
+	}
+
+	if (flags & S_ATIME) {
+		/* to localtime */
+		time64_t seconds = now->tv_sec - fat_tz_offset(sbi);
+		s32 remainder;
+		div_s64_rem(seconds, SECS_PER_DAY, &remainder);
+		/* to day boundary, and back to unix time */
+		seconds = seconds + fat_tz_offset(sbi) - remainder;
+
+		inode->i_atime = (struct timespec64){ seconds, 0 };
+	}
+	if (flags & S_CTIME) {
+		if (sbi->options.isvfat)
+			inode->i_ctime = timespec64_trunc(*now, 10000000);
+		else
+			inode->i_ctime = fat_timespec64_trunc_2secs(*now);
+	}
+	if (flags & S_MTIME)
+		inode->i_mtime = (struct timespec64){ now->tv_sec & ~1, 0 };
+		inode->i_mtime = fat_timespec64_trunc_2secs(*now);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(fat_truncate_time);
+
+int fat_update_time(struct inode *inode, struct timespec64 *now, int flags)
+{
+	int iflags = I_DIRTY_TIME;
+	bool dirty = false;
+
+	if (inode->i_ino == MSDOS_ROOT_INO)
+		return 0;
+
+	fat_truncate_time(inode, now, flags);
+	if (flags & S_VERSION)
+		dirty = inode_maybe_inc_iversion(inode, false);
+	if ((flags & (S_ATIME | S_CTIME | S_MTIME)) &&
+	    !(inode->i_sb->s_flags & SB_LAZYTIME))
+		dirty = true;
+
+	if (dirty)
+		iflags |= I_DIRTY_SYNC;
+	__mark_inode_dirty(inode, iflags);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(fat_update_time);
+
 int fat_sync_bhs(struct buffer_head **bhs, int nr_bhs)
 {
 	int i, err = 0;
diff --git a/fs/fat/namei_msdos.c b/fs/fat/namei_msdos.c
index efb8c40c9d27..effbdd5fbf6e 100644
--- a/fs/fat/namei_msdos.c
+++ b/fs/fat/namei_msdos.c
@@ -637,6 +637,7 @@ static const struct inode_operations msdos_dir_inode_operations = {
 	.rename		= msdos_rename,
 	.setattr	= fat_setattr,
 	.getattr	= fat_getattr,
+	.update_time	= fat_update_time,
 };
 
 static void setup(struct super_block *sb)
diff --git a/fs/fat/namei_vfat.c b/fs/fat/namei_vfat.c
index 82cd1e69cbdf..1daa57cf4bf3 100644
--- a/fs/fat/namei_vfat.c
+++ b/fs/fat/namei_vfat.c
@@ -1032,6 +1032,7 @@ static const struct inode_operations vfat_dir_inode_operations = {
 	.rename		= vfat_rename,
 	.setattr	= fat_setattr,
 	.getattr	= fat_getattr,
+	.update_time	= fat_update_time,
 };
 
 static void setup(struct super_block *sb)
-- 
2.14.4

Re: [PATCH V2 2/4] fat: add functions to update and truncate timestamps appropriately

[OGAWA Hirofumi]

Frank Sorenson <sorenson@redhat.com> writes:

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

> +	if (flags & S_MTIME)
> +		inode->i_mtime = (struct timespec64){ now->tv_sec & ~1, 0 };
> +		inode->i_mtime = fat_timespec64_trunc_2secs(*now);

Looks like the patch is broken. Sent wrong patch?
-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>

[PATCH V4 3/4] fat: change timestamp updates to use fat_truncate_time

[Frank Sorenson]

Convert the inode timestamp updates to use fat_truncate_time.

Signed-off-by: Frank Sorenson <sorenson@redhat.com>
---
 fs/fat/dir.c         |  2 +-
 fs/fat/file.c        |  4 ++--
 fs/fat/inode.c       |  4 ++--
 fs/fat/namei_msdos.c | 16 ++++++++--------
 fs/fat/namei_vfat.c  | 14 +++++++-------
 5 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/fs/fat/dir.c b/fs/fat/dir.c
index 7f5f3699fc6c..1f9bad2c06c7 100644
--- a/fs/fat/dir.c
+++ b/fs/fat/dir.c
@@ -1071,7 +1071,7 @@ int fat_remove_entries(struct inode *dir, struct fat_slot_info *sinfo)
 		}
 	}
 
-	dir->i_mtime = dir->i_atime = current_time(dir);
+	fat_truncate_time(dir, NULL, S_ATIME|S_MTIME);
 	if (IS_DIRSYNC(dir))
 		(void)fat_sync_inode(dir);
 	else
diff --git a/fs/fat/file.c b/fs/fat/file.c
index 19b6b0566411..4b5438405415 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -227,7 +227,7 @@ static int fat_cont_expand(struct inode *inode, loff_t size)
 	if (err)
 		goto out;
 
-	inode->i_ctime = inode->i_mtime = current_time(inode);
+	fat_truncate_time(inode, NULL, S_CTIME|S_MTIME);
 	mark_inode_dirty(inode);
 	if (IS_SYNC(inode)) {
 		int err2;
@@ -330,7 +330,7 @@ static int fat_free(struct inode *inode, int skip)
 		MSDOS_I(inode)->i_logstart = 0;
 	}
 	MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
-	inode->i_ctime = inode->i_mtime = current_time(inode);
+	fat_truncate_time(inode, NULL, S_CTIME|S_MTIME);
 	if (wait) {
 		err = fat_sync_inode(inode);
 		if (err) {
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index 3bf60f19b6d3..c0b5b5c3373b 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -244,7 +244,7 @@ static int fat_write_end(struct file *file, struct address_space *mapping,
 	if (err < len)
 		fat_write_failed(mapping, pos + len);
 	if (!(err < 0) && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {
-		inode->i_mtime = inode->i_ctime = current_time(inode);
+		fat_truncate_time(inode, NULL, S_CTIME|S_MTIME);
 		MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
 		mark_inode_dirty(inode);
 	}
@@ -564,7 +564,7 @@ int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
 				  de->cdate, de->ctime_cs);
 		fat_time_fat2unix(sbi, &inode->i_atime, 0, de->adate, 0);
 	} else
-		inode->i_ctime = inode->i_atime = inode->i_mtime;
+		fat_truncate_time(inode, &inode->i_mtime, S_ATIME|S_CTIME);
 
 	return 0;
 }
diff --git a/fs/fat/namei_msdos.c b/fs/fat/namei_msdos.c
index effbdd5fbf6e..f2cd365a4e86 100644
--- a/fs/fat/namei_msdos.c
+++ b/fs/fat/namei_msdos.c
@@ -250,7 +250,7 @@ static int msdos_add_entry(struct inode *dir, const unsigned char *name,
 	if (err)
 		return err;
 
-	dir->i_ctime = dir->i_mtime = *ts;
+	fat_truncate_time(dir, ts, S_CTIME|S_MTIME);
 	if (IS_DIRSYNC(dir))
 		(void)fat_sync_inode(dir);
 	else
@@ -294,7 +294,7 @@ static int msdos_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 		err = PTR_ERR(inode);
 		goto out;
 	}
-	inode->i_mtime = inode->i_atime = inode->i_ctime = ts;
+	fat_truncate_time(inode, &ts, S_ATIME|S_CTIME|S_MTIME);
 	/* timestamp is already written, so mark_inode_dirty() is unneeded. */
 
 	d_instantiate(dentry, inode);
@@ -327,7 +327,7 @@ static int msdos_rmdir(struct inode *dir, struct dentry *dentry)
 	drop_nlink(dir);
 
 	clear_nlink(inode);
-	inode->i_ctime = current_time(inode);
+	fat_truncate_time(inode, NULL, S_CTIME);
 	fat_detach(inode);
 out:
 	mutex_unlock(&MSDOS_SB(sb)->s_lock);
@@ -380,7 +380,7 @@ static int msdos_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 		goto out;
 	}
 	set_nlink(inode, 2);
-	inode->i_mtime = inode->i_atime = inode->i_ctime = ts;
+	fat_truncate_time(inode, &ts, S_ATIME|S_CTIME|S_MTIME);
 	/* timestamp is already written, so mark_inode_dirty() is unneeded. */
 
 	d_instantiate(dentry, inode);
@@ -413,7 +413,7 @@ static int msdos_unlink(struct inode *dir, struct dentry *dentry)
 	if (err)
 		goto out;
 	clear_nlink(inode);
-	inode->i_ctime = current_time(inode);
+	fat_truncate_time(inode, NULL, S_CTIME);
 	fat_detach(inode);
 out:
 	mutex_unlock(&MSDOS_SB(sb)->s_lock);
@@ -478,7 +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);
-			old_dir->i_ctime = old_dir->i_mtime = current_time(old_dir);
+			fat_truncate_time(old_dir, NULL, S_CTIME|S_MTIME);
 			if (IS_DIRSYNC(old_dir))
 				(void)fat_sync_inode(old_dir);
 			else
@@ -538,7 +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);
-	old_dir->i_ctime = old_dir->i_mtime = ts;
+	fat_truncate_time(old_dir, &ts, S_CTIME|S_MTIME);
 	if (IS_DIRSYNC(old_dir))
 		(void)fat_sync_inode(old_dir);
 	else
@@ -548,7 +548,7 @@ static int do_msdos_rename(struct inode *old_dir, unsigned char *old_name,
 		drop_nlink(new_inode);
 		if (is_dir)
 			drop_nlink(new_inode);
-		new_inode->i_ctime = ts;
+		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 1daa57cf4bf3..996c8c25e9c6 100644
--- a/fs/fat/namei_vfat.c
+++ b/fs/fat/namei_vfat.c
@@ -678,7 +678,7 @@ static int vfat_add_entry(struct inode *dir, const struct qstr *qname,
 		goto cleanup;
 
 	/* update timestamp */
-	dir->i_ctime = dir->i_mtime = dir->i_atime = *ts;
+	fat_truncate_time(dir, ts, S_CTIME|S_MTIME);
 	if (IS_DIRSYNC(dir))
 		(void)fat_sync_inode(dir);
 	else
@@ -779,7 +779,7 @@ static int vfat_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 		goto out;
 	}
 	inode_inc_iversion(inode);
-	inode->i_mtime = inode->i_atime = inode->i_ctime = ts;
+	fat_truncate_time(inode, &ts, S_ATIME|S_CTIME|S_MTIME);
 	/* timestamp is already written, so mark_inode_dirty() is unneeded. */
 
 	d_instantiate(dentry, inode);
@@ -810,7 +810,7 @@ static int vfat_rmdir(struct inode *dir, struct dentry *dentry)
 	drop_nlink(dir);
 
 	clear_nlink(inode);
-	inode->i_mtime = inode->i_atime = current_time(inode);
+	fat_truncate_time(inode, NULL, S_ATIME|S_MTIME);
 	fat_detach(inode);
 	vfat_d_version_set(dentry, inode_query_iversion(dir));
 out:
@@ -836,7 +836,7 @@ static int vfat_unlink(struct inode *dir, struct dentry *dentry)
 	if (err)
 		goto out;
 	clear_nlink(inode);
-	inode->i_mtime = inode->i_atime = current_time(inode);
+	fat_truncate_time(inode, NULL, S_ATIME|S_MTIME);
 	fat_detach(inode);
 	vfat_d_version_set(dentry, inode_query_iversion(dir));
 out:
@@ -876,7 +876,7 @@ static int vfat_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 	}
 	inode_inc_iversion(inode);
 	set_nlink(inode, 2);
-	inode->i_mtime = inode->i_atime = inode->i_ctime = ts;
+	fat_truncate_time(inode, &ts, S_ATIME|S_CTIME|S_MTIME);
 	/* timestamp is already written, so mark_inode_dirty() is unneeded. */
 
 	d_instantiate(dentry, inode);
@@ -969,7 +969,7 @@ static int vfat_rename(struct inode *old_dir, struct dentry *old_dentry,
 	if (err)
 		goto error_dotdot;
 	inode_inc_iversion(old_dir);
-	old_dir->i_ctime = old_dir->i_mtime = ts;
+	fat_truncate_time(old_dir, &ts, S_CTIME|S_MTIME);
 	if (IS_DIRSYNC(old_dir))
 		(void)fat_sync_inode(old_dir);
 	else
@@ -979,7 +979,7 @@ static int vfat_rename(struct inode *old_dir, struct dentry *old_dentry,
 		drop_nlink(new_inode);
 		if (is_dir)
 			drop_nlink(new_inode);
-		new_inode->i_ctime = ts;
+		fat_truncate_time(new_inode, &ts, S_CTIME);
 	}
 out:
 	brelse(sinfo.bh);
-- 
2.14.4

[PATCH V4 4/4] fat: truncate inode timestamp updates in setattr

[Frank Sorenson]

setattr_copy can't truncate timestamps correctly for
msdos/vfat, so truncate and copy them ourselves.

Signed-off-by: Frank Sorenson <sorenson@redhat.com>
---
 fs/fat/file.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/fs/fat/file.c b/fs/fat/file.c
index 4b5438405415..13935ee99e1e 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -542,6 +542,18 @@ int fat_setattr(struct dentry *dentry, struct iattr *attr)
 		up_write(&MSDOS_I(inode)->truncate_lock);
 	}
 
+	/*
+	 * setattr_copy can't truncate these appropriately, so we'll
+	 * copy them ourselves
+	 */
+	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);
+	if (attr->ia_valid & ATTR_MTIME)
+		fat_truncate_time(inode, &attr->ia_mtime, S_MTIME);
+	attr->ia_valid &= ~(ATTR_ATIME|ATTR_CTIME|ATTR_MTIME);
+
 	setattr_copy(inode, attr);
 	mark_inode_dirty(inode);
 out:
-- 
2.14.4