| Message ID | 20221111220614.991928-4-stephen.s.brennan@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | fsnotify: fix softlockups iterating over d_subdirs | expand |
On Sat, Nov 12, 2022 at 12:06 AM Stephen Brennan <stephen.s.brennan@oracle.com> wrote: > > In order to allow sleeping during fsnotify_recalc_mask(), we need to > ensure no callers are holding a spinlock. > > Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com> Reviewed-by: Amir Goldstein <amir73il@gmail.com> small suggestion below. > --- > fs/notify/dnotify/dnotify.c | 28 +++++++++++++++++++--------- > 1 file changed, 19 insertions(+), 9 deletions(-) > > diff --git a/fs/notify/dnotify/dnotify.c b/fs/notify/dnotify/dnotify.c > index 190aa717fa32..a9f05b3cf5ea 100644 > --- a/fs/notify/dnotify/dnotify.c > +++ b/fs/notify/dnotify/dnotify.c > @@ -58,10 +58,10 @@ struct dnotify_mark { > * dnotify cares about for that inode may change. This function runs the > * list of everything receiving dnotify events about this directory and calculates > * the set of all those events. After it updates what dnotify is interested in > - * it calls the fsnotify function so it can update the set of all events relevant > - * to this inode. > + * it returns true if fsnotify_recalc_mask() should be called to update the set > + * of all events related to this inode. > */ > -static void dnotify_recalc_inode_mask(struct fsnotify_mark *fsn_mark) > +static bool dnotify_recalc_inode_mask(struct fsnotify_mark *fsn_mark) > { > __u32 new_mask = 0; > struct dnotify_struct *dn; > @@ -74,10 +74,9 @@ static void dnotify_recalc_inode_mask(struct fsnotify_mark *fsn_mark) > for (dn = dn_mark->dn; dn != NULL; dn = dn->dn_next) > new_mask |= (dn->dn_mask & ~FS_DN_MULTISHOT); > if (fsn_mark->mask == new_mask) > - return; > + return false; > fsn_mark->mask = new_mask; > - > - fsnotify_recalc_mask(fsn_mark->connector); > + return true; > } > > /* > @@ -97,6 +96,7 @@ static int dnotify_handle_event(struct fsnotify_mark *inode_mark, u32 mask, > struct dnotify_struct **prev; > struct fown_struct *fown; > __u32 test_mask = mask & ~FS_EVENT_ON_CHILD; > + bool recalc = false; > > /* not a dir, dnotify doesn't care */ > if (!dir && !(mask & FS_ISDIR)) > @@ -118,12 +118,15 @@ static int dnotify_handle_event(struct fsnotify_mark *inode_mark, u32 mask, > else { > *prev = dn->dn_next; > kmem_cache_free(dnotify_struct_cache, dn); > - dnotify_recalc_inode_mask(inode_mark); > + recalc = dnotify_recalc_inode_mask(inode_mark); > } > } > > spin_unlock(&inode_mark->lock); > > + if (recalc) > + fsnotify_recalc_mask(inode_mark->connector); > + > return 0; > } > > @@ -158,6 +161,7 @@ void dnotify_flush(struct file *filp, fl_owner_t id) > struct dnotify_struct **prev; > struct inode *inode; > bool free = false; > + bool recalc = false; > > inode = file_inode(filp); > if (!S_ISDIR(inode->i_mode)) > @@ -176,7 +180,7 @@ void dnotify_flush(struct file *filp, fl_owner_t id) > if ((dn->dn_owner == id) && (dn->dn_filp == filp)) { > *prev = dn->dn_next; > kmem_cache_free(dnotify_struct_cache, dn); > - dnotify_recalc_inode_mask(fsn_mark); > + recalc = dnotify_recalc_inode_mask(fsn_mark); > break; > } > prev = &dn->dn_next; > @@ -184,6 +188,9 @@ void dnotify_flush(struct file *filp, fl_owner_t id) > > spin_unlock(&fsn_mark->lock); > > + if (recalc) > + fsnotify_recalc_mask(fsn_mark->connector); > + > /* nothing else could have found us thanks to the dnotify_groups > mark_mutex */ > if (dn_mark->dn == NULL) { > @@ -268,6 +275,7 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg) > struct file *f; > int destroy = 0, error = 0; > __u32 mask; > + bool recalc = false; > > /* we use these to tell if we need to kfree */ > new_fsn_mark = NULL; > @@ -377,9 +385,11 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg) > else if (error == -EEXIST) > error = 0; > > - dnotify_recalc_inode_mask(fsn_mark); > + recalc = dnotify_recalc_inode_mask(fsn_mark); > out: > spin_unlock(&fsn_mark->lock); > + if (recalc) > + fsnotify_recalc_mask(fsn_mark->connector); > > if (destroy) > fsnotify_detach_mark(fsn_mark); I'd do else if (recalc) just to emphasise that destroy and recalc are mutually exclusive. Thanks, Amir.
diff --git a/fs/notify/dnotify/dnotify.c b/fs/notify/dnotify/dnotify.c index 190aa717fa32..a9f05b3cf5ea 100644 --- a/fs/notify/dnotify/dnotify.c +++ b/fs/notify/dnotify/dnotify.c @@ -58,10 +58,10 @@ struct dnotify_mark { * dnotify cares about for that inode may change. This function runs the * list of everything receiving dnotify events about this directory and calculates * the set of all those events. After it updates what dnotify is interested in - * it calls the fsnotify function so it can update the set of all events relevant - * to this inode. + * it returns true if fsnotify_recalc_mask() should be called to update the set + * of all events related to this inode. */ -static void dnotify_recalc_inode_mask(struct fsnotify_mark *fsn_mark) +static bool dnotify_recalc_inode_mask(struct fsnotify_mark *fsn_mark) { __u32 new_mask = 0; struct dnotify_struct *dn; @@ -74,10 +74,9 @@ static void dnotify_recalc_inode_mask(struct fsnotify_mark *fsn_mark) for (dn = dn_mark->dn; dn != NULL; dn = dn->dn_next) new_mask |= (dn->dn_mask & ~FS_DN_MULTISHOT); if (fsn_mark->mask == new_mask) - return; + return false; fsn_mark->mask = new_mask; - - fsnotify_recalc_mask(fsn_mark->connector); + return true; } /* @@ -97,6 +96,7 @@ static int dnotify_handle_event(struct fsnotify_mark *inode_mark, u32 mask, struct dnotify_struct **prev; struct fown_struct *fown; __u32 test_mask = mask & ~FS_EVENT_ON_CHILD; + bool recalc = false; /* not a dir, dnotify doesn't care */ if (!dir && !(mask & FS_ISDIR)) @@ -118,12 +118,15 @@ static int dnotify_handle_event(struct fsnotify_mark *inode_mark, u32 mask, else { *prev = dn->dn_next; kmem_cache_free(dnotify_struct_cache, dn); - dnotify_recalc_inode_mask(inode_mark); + recalc = dnotify_recalc_inode_mask(inode_mark); } } spin_unlock(&inode_mark->lock); + if (recalc) + fsnotify_recalc_mask(inode_mark->connector); + return 0; } @@ -158,6 +161,7 @@ void dnotify_flush(struct file *filp, fl_owner_t id) struct dnotify_struct **prev; struct inode *inode; bool free = false; + bool recalc = false; inode = file_inode(filp); if (!S_ISDIR(inode->i_mode)) @@ -176,7 +180,7 @@ void dnotify_flush(struct file *filp, fl_owner_t id) if ((dn->dn_owner == id) && (dn->dn_filp == filp)) { *prev = dn->dn_next; kmem_cache_free(dnotify_struct_cache, dn); - dnotify_recalc_inode_mask(fsn_mark); + recalc = dnotify_recalc_inode_mask(fsn_mark); break; } prev = &dn->dn_next; @@ -184,6 +188,9 @@ void dnotify_flush(struct file *filp, fl_owner_t id) spin_unlock(&fsn_mark->lock); + if (recalc) + fsnotify_recalc_mask(fsn_mark->connector); + /* nothing else could have found us thanks to the dnotify_groups mark_mutex */ if (dn_mark->dn == NULL) { @@ -268,6 +275,7 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg) struct file *f; int destroy = 0, error = 0; __u32 mask; + bool recalc = false; /* we use these to tell if we need to kfree */ new_fsn_mark = NULL; @@ -377,9 +385,11 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg) else if (error == -EEXIST) error = 0; - dnotify_recalc_inode_mask(fsn_mark); + recalc = dnotify_recalc_inode_mask(fsn_mark); out: spin_unlock(&fsn_mark->lock); + if (recalc) + fsnotify_recalc_mask(fsn_mark->connector); if (destroy) fsnotify_detach_mark(fsn_mark);
In order to allow sleeping during fsnotify_recalc_mask(), we need to ensure no callers are holding a spinlock. Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com> --- fs/notify/dnotify/dnotify.c | 28 +++++++++++++++++++--------- 1 file changed, 19 insertions(+), 9 deletions(-)