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Subject[RFC 4/4] shmem: Add support for generic FS events
Date
Add support for the generic FS events interface
covering threshold notifiactions and the ENOSPC
warning.

Signed-off-by: Beata Michalska <b.michalska@samsung.com>
---
mm/shmem.c | 39 ++++++++++++++++++++++++++++++++++++---
1 file changed, 36 insertions(+), 3 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index cf2d0ca..bb261ac 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -201,6 +201,7 @@ static int shmem_reserve_inode(struct super_block *sb)
spin_lock(&sbinfo->stat_lock);
if (!sbinfo->free_inodes) {
spin_unlock(&sbinfo->stat_lock);
+ fs_event_notify(sb, FS_EVENT_WARN, FS_WARN_ENOSPC);
return -ENOSPC;
}
sbinfo->free_inodes--;
@@ -239,8 +240,10 @@ static void shmem_recalc_inode(struct inode *inode)
freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
if (freed > 0) {
struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
- if (sbinfo->max_blocks)
+ if (sbinfo->max_blocks) {
percpu_counter_add(&sbinfo->used_blocks, -freed);
+ fs_event_free_space(inode->i_sb, freed);
+ }
info->alloced -= freed;
inode->i_blocks -= freed * BLOCKS_PER_PAGE;
shmem_unacct_blocks(info->flags, freed);
@@ -1164,6 +1167,7 @@ repeat:
goto unacct;
}
percpu_counter_inc(&sbinfo->used_blocks);
+ fs_event_alloc_space(inode->i_sb, 1);
}

page = shmem_alloc_page(gfp, info, index);
@@ -1245,8 +1249,10 @@ trunc:
spin_unlock(&info->lock);
decused:
sbinfo = SHMEM_SB(inode->i_sb);
- if (sbinfo->max_blocks)
+ if (sbinfo->max_blocks) {
percpu_counter_add(&sbinfo->used_blocks, -1);
+ fs_event_free_space(inode->i_sb, 1);
+ }
unacct:
shmem_unacct_blocks(info->flags, 1);
failed:
@@ -1258,12 +1264,17 @@ unlock:
unlock_page(page);
page_cache_release(page);
}
- if (error == -ENOSPC && !once++) {
+ if (error == -ENOSPC) {
+ if (!once++) {
info = SHMEM_I(inode);
spin_lock(&info->lock);
shmem_recalc_inode(inode);
spin_unlock(&info->lock);
goto repeat;
+ } else {
+ fs_event_notify(inode->i_sb, FS_EVENT_WARN,
+ FS_WARN_ENOSPC);
+ }
}
if (error == -EEXIST) /* from above or from radix_tree_insert */
goto repeat;
@@ -2729,12 +2740,33 @@ static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len,
return 1;
}

+static int shmem_trace_query(struct super_block *sb,
+ struct fs_trace_sdata *data)
+{
+ struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
+
+ if (!sb || !data)
+ return -EINVAL;
+
+ data->events_cap_mask = FS_EVENT_WARN;
+ if (sbinfo->max_blocks) {
+ data->available_blks = sbinfo->max_blocks -
+ percpu_counter_sum(&sbinfo->used_blocks);
+ data->events_cap_mask |= FS_EVENT_THRESH;
+ }
+ return 0;
+}
+
static const struct export_operations shmem_export_ops = {
.get_parent = shmem_get_parent,
.encode_fh = shmem_encode_fh,
.fh_to_dentry = shmem_fh_to_dentry,
};

+static const struct fs_trace_operations shmem_trace_ops = {
+ .fs_trace_query = shmem_trace_query,
+};
+
static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
bool remount)
{
@@ -3020,6 +3052,7 @@ int shmem_fill_super(struct super_block *sb, void *data, int silent)
sb->s_flags |= MS_NOUSER;
}
sb->s_export_op = &shmem_export_ops;
+ sb->s_trace_ops = &shmem_trace_ops;
sb->s_flags |= MS_NOSEC;
#else
sb->s_flags |= MS_NOUSER;
--
1.7.9.5


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