Commit 50e17c00 authored by Deepa Dinamani's avatar Deepa Dinamani
Browse files

vfs: Add timestamp_truncate() api 



timespec_trunc() function is used to truncate a
filesystem timestamp to the right granularity.
But, the function does not clamp tv_sec part of the
timestamps according to the filesystem timestamp limits.

The replacement api: timestamp_truncate() also alters the
signature of the function to accommodate filesystem
timestamp clamping according to flesystem limits.

Note that the tv_nsec part is set to 0 if tv_sec is not within
the range supported for the filesystem.

Signed-off-by: default avatarDeepa Dinamani <deepa.kernel@gmail.com>
Acked-by: default avatarJeff Layton <jlayton@kernel.org>
parent 188d20bc

fs/inode.c

+32 −1
Original line number Diff line number Diff line
@@ -2166,6 +2166,37 @@ struct timespec64 timespec64_trunc(struct timespec64 t, unsigned gran) 
}

EXPORT_SYMBOL(timespec64_trunc);



/**

 * timestamp_truncate - Truncate timespec to a granularity

 * @t: Timespec

 * @inode: inode being updated

 *

 * Truncate a timespec to the granularity supported by the fs

 * containing the inode. Always rounds down. gran must

 * not be 0 nor greater than a second (NSEC_PER_SEC, or 10^9 ns).

 */

struct timespec64 timestamp_truncate(struct timespec64 t, struct inode *inode)

{

	struct super_block *sb = inode->i_sb;

	unsigned int gran = sb->s_time_gran;



	t.tv_sec = clamp(t.tv_sec, sb->s_time_min, sb->s_time_max);

	if (unlikely(t.tv_sec == sb->s_time_max || t.tv_sec == sb->s_time_min))

		t.tv_nsec = 0;



	/* Avoid division in the common cases 1 ns and 1 s. */

	if (gran == 1)

		; /* nothing */

	else if (gran == NSEC_PER_SEC)

		t.tv_nsec = 0;

	else if (gran > 1 && gran < NSEC_PER_SEC)

		t.tv_nsec -= t.tv_nsec % gran;

	else

		WARN(1, "invalid file time granularity: %u", gran);

	return t;

}

EXPORT_SYMBOL(timestamp_truncate);



/**

 * current_time - Return FS time

 * @inode: inode.
@@ -2187,7 +2218,7 @@ struct timespec64 current_time(struct inode *inode) 
		return now;

	}



	return timespec64_trunc(now, inode->i_sb->s_time_gran);

	return timestamp_truncate(now, inode);

}

EXPORT_SYMBOL(current_time);

include/linux/fs.h

+2 −0
Original line number Diff line number Diff line
@@ -726,6 +726,8 @@ struct inode { 
	void			*i_private; /* fs or device private pointer */

} __randomize_layout;



struct timespec64 timestamp_truncate(struct timespec64 t, struct inode *inode);



static inline unsigned int i_blocksize(const struct inode *node)

{

	return (1 << node->i_blkbits);

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