From: Yu Zhao Date: Tue, 8 Sep 2015 22:03:33 +0000 (-0700) Subject: shmem: recalculate file inode when fstat X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=44a30220bc0a;p=openwrt%2Fstaging%2Fblogic.git 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 This makes fstat sometimes return out-of-date block size.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 Signed-off-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/shmem.c b/mm/shmem.c index dbe0c1e8349c..48ce82926d93 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -542,6 +542,21 @@ void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) } 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 file_operations shmem_file_operations = { }; static const struct inode_operations shmem_inode_operations = { + .getattr = shmem_getattr, .setattr = shmem_setattr, #ifdef CONFIG_TMPFS_XATTR .setxattr = shmem_setxattr,