Commit 719ee344 authored by Steven Whitehouse's avatar Steven Whitehouse
Browse files

GFS2: high time to take some time over atime 



Until now, we've used the same scheme as GFS1 for atime. This has failed
since atime is a per vfsmnt flag, not a per fs flag and as such the
"noatime" flag was not getting passed down to the filesystems. This
patch removes all the "special casing" around atime updates and we
simply use the VFS's atime code.

The net result is that GFS2 will now support all the same atime related
mount options of any other filesystem on a per-vfsmnt basis. We do lose
the "lazy atime" updates, but we gain "relatime". We could add lazy
atime to the VFS at a later date, if there is a requirement for that
variant still - I suspect relatime will be enough.

Also we lose about 100 lines of code after this patch has been applied,
and I have a suspicion that it will speed things up a bit, even when
atime is "on". So it seems like a nice clean up as well.

From a user perspective, everything stays the same except the loss of
the per-fs atime quantum tweekable (ought to be per-vfsmnt at the very
least, and to be honest I don't think anybody ever used it) and that a
number of options which were ignored before now work correctly.

Please let me know if you've got any comments. I'm pushing this out
early so that you can all see what my plans are.

Signed-off-by: default avatarSteven Whitehouse <swhiteho@redhat.com>
parent 37ec89e8

fs/gfs2/glock.c

+0 −2
Original line number Diff line number Diff line
@@ -1580,8 +1580,6 @@ static const char *hflags2str(char *buf, unsigned flags, unsigned long iflags) 
		*p++ = 'a';

	if (flags & GL_EXACT)

		*p++ = 'E';

	if (flags & GL_ATIME)

		*p++ = 'a';

	if (flags & GL_NOCACHE)

		*p++ = 'c';

	if (test_bit(HIF_HOLDER, &iflags))

fs/gfs2/glock.h

+0 −1
Original line number Diff line number Diff line
@@ -24,7 +24,6 @@ 
#define GL_ASYNC		0x00000040

#define GL_EXACT		0x00000080

#define GL_SKIP			0x00000100

#define GL_ATIME		0x00000200

#define GL_NOCACHE		0x00000400



#define GLR_TRYFAILED		13

fs/gfs2/incore.h

+0 −2
Original line number Diff line number Diff line
@@ -420,7 +420,6 @@ struct gfs2_tune { 
	unsigned int gt_quota_scale_den; /* Denominator */

	unsigned int gt_quota_cache_secs;

	unsigned int gt_quota_quantum; /* Secs between syncs to quota file */

	unsigned int gt_atime_quantum; /* Min secs between atime updates */

	unsigned int gt_new_files_jdata;

	unsigned int gt_max_readahead; /* Max bytes to read-ahead from disk */

	unsigned int gt_stall_secs; /* Detects trouble! */
@@ -433,7 +432,6 @@ enum { 
	SDF_JOURNAL_CHECKED	= 0,

	SDF_JOURNAL_LIVE	= 1,

	SDF_SHUTDOWN		= 2,

	SDF_NOATIME		= 3,

};



#define GFS2_FSNAME_LEN		256

fs/gfs2/inode.c

+8 −99
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#include <linux/crc32.h>

#include <linux/lm_interface.h>

#include <linux/security.h>

#include <linux/time.h>



#include "gfs2.h"

#include "incore.h"
@@ -249,6 +250,7 @@ static int gfs2_dinode_in(struct gfs2_inode *ip, const void *buf) 
{

	struct gfs2_dinode_host *di = &ip->i_di;

	const struct gfs2_dinode *str = buf;

	struct timespec atime;

	u16 height, depth;



	if (unlikely(ip->i_no_addr != be64_to_cpu(str->di_num.no_addr)))
@@ -275,8 +277,10 @@ static int gfs2_dinode_in(struct gfs2_inode *ip, const void *buf) 
	di->di_size = be64_to_cpu(str->di_size);

	i_size_write(&ip->i_inode, di->di_size);

	gfs2_set_inode_blocks(&ip->i_inode, be64_to_cpu(str->di_blocks));

	ip->i_inode.i_atime.tv_sec = be64_to_cpu(str->di_atime);

	ip->i_inode.i_atime.tv_nsec = be32_to_cpu(str->di_atime_nsec);

	atime.tv_sec = be64_to_cpu(str->di_atime);

	atime.tv_nsec = be32_to_cpu(str->di_atime_nsec);

	if (timespec_compare(&ip->i_inode.i_atime, &atime) < 0)

		ip->i_inode.i_atime = atime;

	ip->i_inode.i_mtime.tv_sec = be64_to_cpu(str->di_mtime);

	ip->i_inode.i_mtime.tv_nsec = be32_to_cpu(str->di_mtime_nsec);

	ip->i_inode.i_ctime.tv_sec = be64_to_cpu(str->di_ctime);
@@ -1157,8 +1161,8 @@ int gfs2_readlinki(struct gfs2_inode *ip, char **buf, unsigned int *len) 
	unsigned int x;

	int error;



	gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME, &i_gh);

	error = gfs2_glock_nq_atime(&i_gh);

	gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &i_gh);

	error = gfs2_glock_nq(&i_gh);

	if (error) {

		gfs2_holder_uninit(&i_gh);

		return error;
@@ -1193,101 +1197,6 @@ out: 
	return error;

}



/**

 * gfs2_glock_nq_atime - Acquire a hold on an inode's glock, and

 *       conditionally update the inode's atime

 * @gh: the holder to acquire

 *

 * Tests atime (access time) for gfs2_read, gfs2_readdir and gfs2_mmap

 * Update if the difference between the current time and the inode's current

 * atime is greater than an interval specified at mount.

 *

 * Returns: errno

 */



int gfs2_glock_nq_atime(struct gfs2_holder *gh)

{

	struct gfs2_glock *gl = gh->gh_gl;

	struct gfs2_sbd *sdp = gl->gl_sbd;

	struct gfs2_inode *ip = gl->gl_object;

	s64 quantum = gfs2_tune_get(sdp, gt_atime_quantum);

	unsigned int state;

	int flags;

	int error;

	struct timespec tv = CURRENT_TIME;



	if (gfs2_assert_warn(sdp, gh->gh_flags & GL_ATIME) ||

	    gfs2_assert_warn(sdp, !(gh->gh_flags & GL_ASYNC)) ||

	    gfs2_assert_warn(sdp, gl->gl_ops == &gfs2_inode_glops))

		return -EINVAL;



	state = gh->gh_state;

	flags = gh->gh_flags;



	error = gfs2_glock_nq(gh);

	if (error)

		return error;



	if (test_bit(SDF_NOATIME, &sdp->sd_flags) ||

	    (sdp->sd_vfs->s_flags & MS_RDONLY))

		return 0;



	if (tv.tv_sec - ip->i_inode.i_atime.tv_sec >= quantum) {

		gfs2_glock_dq(gh);

		gfs2_holder_reinit(LM_ST_EXCLUSIVE, gh->gh_flags & ~LM_FLAG_ANY,

				   gh);

		error = gfs2_glock_nq(gh);

		if (error)

			return error;



		/* Verify that atime hasn't been updated while we were

		   trying to get exclusive lock. */



		tv = CURRENT_TIME;

		if (tv.tv_sec - ip->i_inode.i_atime.tv_sec >= quantum) {

			struct buffer_head *dibh;

			struct gfs2_dinode *di;



			error = gfs2_trans_begin(sdp, RES_DINODE, 0);

			if (error == -EROFS)

				return 0;

			if (error)

				goto fail;



			error = gfs2_meta_inode_buffer(ip, &dibh);

			if (error)

				goto fail_end_trans;



			ip->i_inode.i_atime = tv;



			gfs2_trans_add_bh(ip->i_gl, dibh, 1);

			di = (struct gfs2_dinode *)dibh->b_data;

			di->di_atime = cpu_to_be64(ip->i_inode.i_atime.tv_sec);

			di->di_atime_nsec = cpu_to_be32(ip->i_inode.i_atime.tv_nsec);

			brelse(dibh);



			gfs2_trans_end(sdp);

		}



		/* If someone else has asked for the glock,

		   unlock and let them have it. Then reacquire

		   in the original state. */

		if (gfs2_glock_is_blocking(gl)) {

			gfs2_glock_dq(gh);

			gfs2_holder_reinit(state, flags, gh);

			return gfs2_glock_nq(gh);

		}

	}



	return 0;



fail_end_trans:

	gfs2_trans_end(sdp);

fail:

	gfs2_glock_dq(gh);

	return error;

}



static int

__gfs2_setattr_simple(struct gfs2_inode *ip, struct iattr *attr)

{

fs/gfs2/inode.h

+0 −1
Original line number Diff line number Diff line
@@ -92,7 +92,6 @@ int gfs2_unlink_ok(struct gfs2_inode *dip, const struct qstr *name, 
		   const struct gfs2_inode *ip);

int gfs2_permission(struct inode *inode, int mask);

int gfs2_readlinki(struct gfs2_inode *ip, char **buf, unsigned int *len);

int gfs2_glock_nq_atime(struct gfs2_holder *gh);

int gfs2_setattr_simple(struct gfs2_inode *ip, struct iattr *attr);

struct inode *gfs2_lookup_simple(struct inode *dip, const char *name);

void gfs2_dinode_out(const struct gfs2_inode *ip, void *buf);

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