shmem: recalculate file inode when fstat
Shmem uses shmem_recalc_inode to update i_blocks when it allocates page,
undoes range or swaps. But mm can drop clean page without notifying
shmem. This makes fstat sometimes return out-of-date block size.
The problem can be partially solved when we add
inode_operations->getattr which calls shmem_recalc_inode to update
i_blocks for fstat.
shmem_recalc_inode also updates counter used by statfs and
vm_committed_as. For them the situation is not changed. They still
suffer from the discrepancy after dropping clean page and before the
function is called by aforementioned triggers.
Signed-off-by: Yu Zhao <yuzhao@google.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/shmem.c b/mm/shmem.c
index dbe0c1e..48ce829 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -542,6 +542,21 @@
}
EXPORT_SYMBOL_GPL(shmem_truncate_range);
+static int shmem_getattr(struct vfsmount *mnt, struct dentry *dentry,
+ struct kstat *stat)
+{
+ struct inode *inode = dentry->d_inode;
+ struct shmem_inode_info *info = SHMEM_I(inode);
+
+ spin_lock(&info->lock);
+ shmem_recalc_inode(inode);
+ spin_unlock(&info->lock);
+
+ generic_fillattr(inode, stat);
+
+ return 0;
+}
+
static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
{
struct inode *inode = d_inode(dentry);
@@ -3122,6 +3137,7 @@
};
static const struct inode_operations shmem_inode_operations = {
+ .getattr = shmem_getattr,
.setattr = shmem_setattr,
#ifdef CONFIG_TMPFS_XATTR
.setxattr = shmem_setxattr,