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-rw-r--r--Documentation/filesystems/vfs.txt16
-rw-r--r--fs/super.c45
-rw-r--r--include/linux/fs.h2
3 files changed, 51 insertions, 12 deletions
diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index d56151f..fd24f34 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -229,6 +229,8 @@ struct super_operations {
ssize_t (*quota_read)(struct super_block *, int, char *, size_t, loff_t);
ssize_t (*quota_write)(struct super_block *, int, const char *, size_t, loff_t);
+ int (*nr_cached_objects)(struct super_block *);
+ void (*free_cached_objects)(struct super_block *, int);
};
All methods are called without any locks being held, unless otherwise
@@ -301,6 +303,20 @@ or bottom half).
quota_write: called by the VFS to write to filesystem quota file.
+ nr_cached_objects: called by the sb cache shrinking function for the
+ filesystem to return the number of freeable cached objects it contains.
+ Optional.
+
+ free_cache_objects: called by the sb cache shrinking function for the
+ filesystem to scan the number of objects indicated to try to free them.
+ Optional, but any filesystem implementing this method needs to also
+ implement ->nr_cached_objects for it to be called correctly.
+
+ We can't do anything with any errors that the filesystem might
+ encountered, hence the void return type. This will never be called if
+ the VM is trying to reclaim under GFP_NOFS conditions, hence this
+ method does not need to handle that situation itself.
+
Whoever sets up the inode is responsible for filling in the "i_op" field. This
is a pointer to a "struct inode_operations" which describes the methods that
can be performed on individual inodes.
diff --git a/fs/super.c b/fs/super.c
index 37a7541..5101f05 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -48,7 +48,8 @@ DEFINE_SPINLOCK(sb_lock);
static int prune_super(struct shrinker *shrink, struct shrink_control *sc)
{
struct super_block *sb;
- int count;
+ int fs_objects = 0;
+ int total_objects;
sb = container_of(shrink, struct super_block, s_shrink);
@@ -62,22 +63,42 @@ static int prune_super(struct shrinker *shrink, struct shrink_control *sc)
if (!grab_super_passive(sb))
return -1;
- if (sc->nr_to_scan) {
- /* proportion the scan between the two caches */
- int total;
+ if (sb->s_op && sb->s_op->nr_cached_objects)
+ fs_objects = sb->s_op->nr_cached_objects(sb);
+
+ total_objects = sb->s_nr_dentry_unused +
+ sb->s_nr_inodes_unused + fs_objects + 1;
- total = sb->s_nr_dentry_unused + sb->s_nr_inodes_unused + 1;
- count = (sc->nr_to_scan * sb->s_nr_dentry_unused) / total;
+ if (sc->nr_to_scan) {
+ int dentries;
+ int inodes;
+
+ /* proportion the scan between the caches */
+ dentries = (sc->nr_to_scan * sb->s_nr_dentry_unused) /
+ total_objects;
+ inodes = (sc->nr_to_scan * sb->s_nr_inodes_unused) /
+ total_objects;
+ if (fs_objects)
+ fs_objects = (sc->nr_to_scan * fs_objects) /
+ total_objects;
+ /*
+ * prune the dcache first as the icache is pinned by it, then
+ * prune the icache, followed by the filesystem specific caches
+ */
+ prune_dcache_sb(sb, dentries);
+ prune_icache_sb(sb, inodes);
- /* prune dcache first as icache is pinned by it */
- prune_dcache_sb(sb, count);
- prune_icache_sb(sb, sc->nr_to_scan - count);
+ if (fs_objects && sb->s_op->free_cached_objects) {
+ sb->s_op->free_cached_objects(sb, fs_objects);
+ fs_objects = sb->s_op->nr_cached_objects(sb);
+ }
+ total_objects = sb->s_nr_dentry_unused +
+ sb->s_nr_inodes_unused + fs_objects;
}
- count = ((sb->s_nr_dentry_unused + sb->s_nr_inodes_unused) / 100)
- * sysctl_vfs_cache_pressure;
+ total_objects = (total_objects / 100) * sysctl_vfs_cache_pressure;
drop_super(sb);
- return count;
+ return total_objects;
}
/**
diff --git a/include/linux/fs.h b/include/linux/fs.h
index d7f35e90..1393742 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1655,6 +1655,8 @@ struct super_operations {
ssize_t (*quota_write)(struct super_block *, int, const char *, size_t, loff_t);
#endif
int (*bdev_try_to_free_page)(struct super_block*, struct page*, gfp_t);
+ int (*nr_cached_objects)(struct super_block *);
+ void (*free_cached_objects)(struct super_block *, int);
};
/*
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