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-rw-r--r--mm/shmem.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index 4ae47f5..c919ed5 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -80,6 +80,7 @@
enum sgp_type {
SGP_READ, /* don't exceed i_size, don't allocate page */
SGP_CACHE, /* don't exceed i_size, may allocate page */
+ SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */
SGP_WRITE, /* may exceed i_size, may allocate page */
};
@@ -1333,6 +1334,8 @@ repeat:
clear_highpage(filepage);
flush_dcache_page(filepage);
SetPageUptodate(filepage);
+ if (sgp == SGP_DIRTY)
+ set_page_dirty(filepage);
}
done:
*pagep = filepage;
@@ -1518,6 +1521,15 @@ static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_
struct inode *inode = filp->f_path.dentry->d_inode;
struct address_space *mapping = inode->i_mapping;
unsigned long index, offset;
+ enum sgp_type sgp = SGP_READ;
+
+ /*
+ * Might this read be for a stacking filesystem? Then when reading
+ * holes of a sparse file, we actually need to allocate those pages,
+ * and even mark them dirty, so it cannot exceed the max_blocks limit.
+ */
+ if (segment_eq(get_fs(), KERNEL_DS))
+ sgp = SGP_DIRTY;
index = *ppos >> PAGE_CACHE_SHIFT;
offset = *ppos & ~PAGE_CACHE_MASK;
@@ -1536,7 +1548,7 @@ static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_
break;
}
- desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL);
+ desc->error = shmem_getpage(inode, index, &page, sgp, NULL);
if (desc->error) {
if (desc->error == -EINVAL)
desc->error = 0;
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