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    SubjectRe: [RFCv2][PATCH 4/7] fsnotify: encapsulate embedded fsnotify data in a single spot
    On Wed 24-06-15 17:16:07, Dave Hansen wrote:
    >
    > From: Dave Hansen <dave.hansen@linux.intel.com>
    >
    > Both inodes and vfsmounts have fsnotify data embedded in them.
    > The data is always a "mask" and a "mark". Take those two
    > fields and move them in to a new structure: struct fsnotify_head.
    >
    > We will shortly be adding a new field to this.
    >
    > This also lets us get rid of the ugly #ifdef in 'struct inode'.
    >
    > In searching for i_fsnotify_mark, my regex found the fsnotify_mark
    > comment about g_list. I think the comment was wrong and corrected
    > it.

    Umm, doesn't this grow struct inode due to padding? I'm not sure whether the
    compiler is clever enough to leave the first 32-bit variable only 32-bit
    aligned when it is inside a struct (at least my quick test seems to show it
    isn't)...

    Honza

    >
    > Cc: Jan Kara <jack@suse.cz>
    > Cc: Alexander Viro <viro@zeniv.linux.org.uk>
    > Cc: linux-fsdevel@vger.kernel.org
    > Cc: linux-kernel@vger.kernel.org
    > Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
    > Cc: Tim Chen <tim.c.chen@linux.intel.com>
    > Cc: Andi Kleen <ak@linux.intel.com>
    > Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
    > ---
    >
    > b/fs/inode.c | 4 ++--
    > b/fs/notify/fanotify/fanotify_user.c | 4 ++--
    > b/fs/notify/fsnotify.c | 12 ++++++------
    > b/fs/notify/inode_mark.c | 18 +++++++++---------
    > b/fs/notify/inotify/inotify_user.c | 2 +-
    > b/include/linux/fs.h | 6 ++----
    > b/include/linux/fsnotify_backend.h | 8 ++++----
    > b/include/linux/fsnotify_head.h | 17 +++++++++++++++++
    > b/kernel/auditsc.c | 4 ++--
    > 9 files changed, 45 insertions(+), 30 deletions(-)
    >
    > diff -puN fs/inode.c~fsnotify_head fs/inode.c
    > --- a/fs/inode.c~fsnotify_head 2015-06-24 17:14:35.694159644 -0700
    > +++ b/fs/inode.c 2015-06-24 17:14:35.711160408 -0700
    > @@ -181,7 +181,7 @@ int inode_init_always(struct super_block
    > #endif
    >
    > #ifdef CONFIG_FSNOTIFY
    > - inode->i_fsnotify_mask = 0;
    > + inode->i_fsnotify.mask = 0;
    > #endif
    > inode->i_flctx = NULL;
    > this_cpu_inc(nr_inodes);
    > @@ -363,7 +363,7 @@ void inode_init_once(struct inode *inode
    > address_space_init_once(&inode->i_data);
    > i_size_ordered_init(inode);
    > #ifdef CONFIG_FSNOTIFY
    > - INIT_HLIST_HEAD(&inode->i_fsnotify_marks);
    > + INIT_HLIST_HEAD(&inode->i_fsnotify.marks);
    > #endif
    > }
    > EXPORT_SYMBOL(inode_init_once);
    > diff -puN fs/notify/fanotify/fanotify_user.c~fsnotify_head fs/notify/fanotify/fanotify_user.c
    > --- a/fs/notify/fanotify/fanotify_user.c~fsnotify_head 2015-06-24 17:14:35.696159734 -0700
    > +++ b/fs/notify/fanotify/fanotify_user.c 2015-06-24 17:14:35.712160453 -0700
    > @@ -562,7 +562,7 @@ static int fanotify_remove_inode_mark(st
    >
    > /* matches the fsnotify_find_inode_mark() */
    > fsnotify_put_mark(fsn_mark);
    > - if (removed & inode->i_fsnotify_mask)
    > + if (removed & inode->i_fsnotify.mask)
    > fsnotify_recalc_inode_mask(inode);
    >
    > return 0;
    > @@ -679,7 +679,7 @@ static int fanotify_add_inode_mark(struc
    > added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
    > mutex_unlock(&group->mark_mutex);
    >
    > - if (added & ~inode->i_fsnotify_mask)
    > + if (added & ~inode->i_fsnotify.mask)
    > fsnotify_recalc_inode_mask(inode);
    >
    > fsnotify_put_mark(fsn_mark);
    > diff -puN fs/notify/fsnotify.c~fsnotify_head fs/notify/fsnotify.c
    > --- a/fs/notify/fsnotify.c~fsnotify_head 2015-06-24 17:14:35.697159779 -0700
    > +++ b/fs/notify/fsnotify.c 2015-06-24 17:14:35.712160453 -0700
    > @@ -104,7 +104,7 @@ int __fsnotify_parent(struct path *path,
    >
    > if (unlikely(!fsnotify_inode_watches_children(p_inode)))
    > __fsnotify_update_child_dentry_flags(p_inode);
    > - else if (p_inode->i_fsnotify_mask & mask) {
    > + else if (p_inode->i_fsnotify.mask & mask) {
    > /* we are notifying a parent so come up with the new mask which
    > * specifies these are events which came from a child. */
    > mask |= FS_EVENT_ON_CHILD;
    > @@ -210,7 +210,7 @@ int fsnotify(struct inode *to_tell, __u3
    > * this type of event.
    > */
    > if (!(mask & FS_MODIFY) &&
    > - !(test_mask & to_tell->i_fsnotify_mask) &&
    > + !(test_mask & to_tell->i_fsnotify.mask) &&
    > !(mnt && test_mask & mnt->mnt_fsnotify_mask))
    > return 0;
    > /*
    > @@ -220,22 +220,22 @@ int fsnotify(struct inode *to_tell, __u3
    > * SRCU because we have no references to any objects and do not
    > * need SRCU to keep them "alive".
    > */
    > - if (!to_tell->i_fsnotify_marks.first &&
    > + if (!to_tell->i_fsnotify.marks.first &&
    > (!mnt || !mnt->mnt_fsnotify_marks.first))
    > return 0;
    >
    > idx = srcu_read_lock(&fsnotify_mark_srcu);
    >
    > if ((mask & FS_MODIFY) ||
    > - (test_mask & to_tell->i_fsnotify_mask))
    > - inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first,
    > + (test_mask & to_tell->i_fsnotify.mask))
    > + inode_node = srcu_dereference(to_tell->i_fsnotify.marks.first,
    > &fsnotify_mark_srcu);
    >
    > if (mnt && ((mask & FS_MODIFY) ||
    > (test_mask & mnt->mnt_fsnotify_mask))) {
    > vfsmount_node = srcu_dereference(mnt->mnt_fsnotify_marks.first,
    > &fsnotify_mark_srcu);
    > - inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first,
    > + inode_node = srcu_dereference(to_tell->i_fsnotify.marks.first,
    > &fsnotify_mark_srcu);
    > }
    >
    > diff -puN fs/notify/inode_mark.c~fsnotify_head fs/notify/inode_mark.c
    > --- a/fs/notify/inode_mark.c~fsnotify_head 2015-06-24 17:14:35.699159868 -0700
    > +++ b/fs/notify/inode_mark.c 2015-06-24 17:14:35.712160453 -0700
    > @@ -31,13 +31,13 @@
    > #include "../internal.h"
    >
    > /*
    > - * Recalculate the inode->i_fsnotify_mask, or the mask of all FS_* event types
    > + * Recalculate the inode->i_fsnotify.mask, or the mask of all FS_* event types
    > * any notifier is interested in hearing for this inode.
    > */
    > void fsnotify_recalc_inode_mask(struct inode *inode)
    > {
    > spin_lock(&inode->i_lock);
    > - inode->i_fsnotify_mask = fsnotify_recalc_mask(&inode->i_fsnotify_marks);
    > + inode->i_fsnotify.mask = fsnotify_recalc_mask(&inode->i_fsnotify.marks);
    > spin_unlock(&inode->i_lock);
    >
    > __fsnotify_update_child_dentry_flags(inode);
    > @@ -56,11 +56,11 @@ void fsnotify_destroy_inode_mark(struct
    > mark->inode = NULL;
    >
    > /*
    > - * this mark is now off the inode->i_fsnotify_marks list and we
    > + * this mark is now off the inode->i_fsnotify.marks list and we
    > * hold the inode->i_lock, so this is the perfect time to update the
    > - * inode->i_fsnotify_mask
    > + * inode->i_fsnotify.mask
    > */
    > - inode->i_fsnotify_mask = fsnotify_recalc_mask(&inode->i_fsnotify_marks);
    > + inode->i_fsnotify.mask = fsnotify_recalc_mask(&inode->i_fsnotify.marks);
    > spin_unlock(&inode->i_lock);
    > }
    >
    > @@ -74,7 +74,7 @@ void fsnotify_clear_marks_by_inode(struc
    > LIST_HEAD(free_list);
    >
    > spin_lock(&inode->i_lock);
    > - hlist_for_each_entry_safe(mark, n, &inode->i_fsnotify_marks, obj_list) {
    > + hlist_for_each_entry_safe(mark, n, &inode->i_fsnotify.marks, obj_list) {
    > list_add(&mark->free_list, &free_list);
    > hlist_del_init_rcu(&mark->obj_list);
    > fsnotify_get_mark(mark);
    > @@ -102,7 +102,7 @@ struct fsnotify_mark *fsnotify_find_inod
    > struct fsnotify_mark *mark;
    >
    > spin_lock(&inode->i_lock);
    > - mark = fsnotify_find_mark(&inode->i_fsnotify_marks, group);
    > + mark = fsnotify_find_mark(&inode->i_fsnotify.marks, group);
    > spin_unlock(&inode->i_lock);
    >
    > return mark;
    > @@ -153,9 +153,9 @@ int fsnotify_add_inode_mark(struct fsnot
    >
    > spin_lock(&inode->i_lock);
    > mark->inode = inode;
    > - ret = fsnotify_add_mark_list(&inode->i_fsnotify_marks, mark,
    > + ret = fsnotify_add_mark_list(&inode->i_fsnotify.marks, mark,
    > allow_dups);
    > - inode->i_fsnotify_mask = fsnotify_recalc_mask(&inode->i_fsnotify_marks);
    > + inode->i_fsnotify.mask = fsnotify_recalc_mask(&inode->i_fsnotify.marks);
    > spin_unlock(&inode->i_lock);
    >
    > return ret;
    > diff -puN fs/notify/inotify/inotify_user.c~fsnotify_head fs/notify/inotify/inotify_user.c
    > --- a/fs/notify/inotify/inotify_user.c~fsnotify_head 2015-06-24 17:14:35.701159959 -0700
    > +++ b/fs/notify/inotify/inotify_user.c 2015-06-24 17:14:35.713160498 -0700
    > @@ -547,7 +547,7 @@ static int inotify_update_existing_watch
    > /* more bits in old than in new? */
    > int dropped = (old_mask & ~new_mask);
    > /* more bits in this fsn_mark than the inode's mask? */
    > - int do_inode = (new_mask & ~inode->i_fsnotify_mask);
    > + int do_inode = (new_mask & ~inode->i_fsnotify.mask);
    >
    > /* update the inode with this new fsn_mark */
    > if (dropped || do_inode)
    > diff -puN include/linux/fs.h~fsnotify_head include/linux/fs.h
    > --- a/include/linux/fs.h~fsnotify_head 2015-06-24 17:14:35.702160003 -0700
    > +++ b/include/linux/fs.h 2015-06-24 17:14:35.710160363 -0700
    > @@ -30,6 +30,7 @@
    > #include <linux/lockdep.h>
    > #include <linux/percpu-rwsem.h>
    > #include <linux/blk_types.h>
    > +#include <linux/fsnotify_head.h>
    >
    > #include <asm/byteorder.h>
    > #include <uapi/linux/fs.h>
    > @@ -660,10 +661,7 @@ struct inode {
    >
    > __u32 i_generation;
    >
    > -#ifdef CONFIG_FSNOTIFY
    > - __u32 i_fsnotify_mask; /* all events this inode cares about */
    > - struct hlist_head i_fsnotify_marks;
    > -#endif
    > + struct fsnotify_head i_fsnotify;
    >
    > void *i_private; /* fs or device private pointer */
    > };
    > diff -puN include/linux/fsnotify_backend.h~fsnotify_head include/linux/fsnotify_backend.h
    > --- a/include/linux/fsnotify_backend.h~fsnotify_head 2015-06-24 17:14:35.704160093 -0700
    > +++ b/include/linux/fsnotify_backend.h 2015-06-24 17:14:35.709160318 -0700
    > @@ -212,7 +212,7 @@ struct fsnotify_mark {
    > * in kernel that found and may be using this mark. */
    > atomic_t refcnt; /* active things looking at this mark */
    > struct fsnotify_group *group; /* group this mark is for */
    > - struct list_head g_list; /* list of marks by group->i_fsnotify_marks
    > + struct list_head g_list; /* list of marks by group->marks_list
    > * Also reused for queueing mark into
    > * destroy_list when it's waiting for
    > * the end of SRCU period before it can
    > @@ -249,11 +249,11 @@ extern u32 fsnotify_get_cookie(void);
    > static inline int fsnotify_inode_watches_children(struct inode *inode)
    > {
    > /* FS_EVENT_ON_CHILD is set if the inode may care */
    > - if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD))
    > + if (!(inode->i_fsnotify.mask & FS_EVENT_ON_CHILD))
    > return 0;
    > /* this inode might care about child events, does it care about the
    > * specific set of events that can happen on a child? */
    > - return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD;
    > + return inode->i_fsnotify.mask & FS_EVENTS_POSS_ON_CHILD;
    > }
    >
    > /*
    > @@ -326,7 +326,7 @@ extern struct fsnotify_event *fsnotify_r
    >
    > /* run all marks associated with a vfsmount and update mnt->mnt_fsnotify_mask */
    > extern void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt);
    > -/* run all marks associated with an inode and update inode->i_fsnotify_mask */
    > +/* run all marks associated with an inode and update inode->i_fsnotify.mask */
    > extern void fsnotify_recalc_inode_mask(struct inode *inode);
    > extern void fsnotify_init_mark(struct fsnotify_mark *mark, void (*free_mark)(struct fsnotify_mark *mark));
    > /* find (and take a reference) to a mark associated with group and inode */
    > diff -puN /dev/null include/linux/fsnotify_head.h
    > --- /dev/null 2015-06-17 12:44:31.632705131 -0700
    > +++ b/include/linux/fsnotify_head.h 2015-06-24 17:14:35.711160408 -0700
    > @@ -0,0 +1,17 @@
    > +#ifndef __LINUX_FSNOTIFY_HEAD_H
    > +#define __LINUX_FSNOTIFY_HEAD_H
    > +
    > +#include <linux/types.h>
    > +
    > +/*
    > + * This gets embedded in vfsmounts and inodes.
    > + */
    > +
    > +struct fsnotify_head {
    > +#ifdef CONFIG_FSNOTIFY
    > + __u32 mask; /* all events this object cares about */
    > + struct hlist_head marks;
    > +#endif
    > +};
    > +
    > +#endif /* __LINUX_FSNOTIFY_HEAD_H */
    > diff -puN kernel/auditsc.c~fsnotify_head kernel/auditsc.c
    > --- a/kernel/auditsc.c~fsnotify_head 2015-06-24 17:14:35.706160183 -0700
    > +++ b/kernel/auditsc.c 2015-06-24 17:14:35.714160543 -0700
    > @@ -1587,7 +1587,7 @@ static inline void handle_one(const stru
    > struct audit_tree_refs *p;
    > struct audit_chunk *chunk;
    > int count;
    > - if (likely(hlist_empty(&inode->i_fsnotify_marks)))
    > + if (likely(hlist_empty(&inode->i_fsnotify.marks)))
    > return;
    > context = current->audit_context;
    > p = context->trees;
    > @@ -1630,7 +1630,7 @@ retry:
    > seq = read_seqbegin(&rename_lock);
    > for(;;) {
    > struct inode *inode = d_backing_inode(d);
    > - if (inode && unlikely(!hlist_empty(&inode->i_fsnotify_marks))) {
    > + if (inode && unlikely(!hlist_empty(&inode->i_fsnotify.marks))) {
    > struct audit_chunk *chunk;
    > chunk = audit_tree_lookup(inode);
    > if (chunk) {
    > _
    --
    Jan Kara <jack@suse.cz>
    SUSE Labs, CR


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