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authorWengang Wang <wen.gang.wang@oracle.com>2011-07-24 10:36:54 -0700
committerSunil Mushran <sunil.mushran@oracle.com>2011-07-24 10:36:54 -0700
commit5cffff9e29866a3de98c2c25135b3199491f93b0 (patch)
tree11b53cb3ad7cb44adb80f7802a62c145bf713514 /fs/ocfs2/mmap.c
parenta035bff6b82aca89c1223e2c614adc2d17ec8aa2 (diff)
ocfs2: Fix ocfs2_page_mkwrite()
This patch address two shortcomings in ocfs2_page_mkwrite(): 1. Makes the function return better VM_FAULT_* errors. 2. It handles a error that is triggered when a page is dropped from the mapping due to memory pressure. This patch locks the page to prevent that. [Patch was cleaned up by Sunil Mushran.] Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com> Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Diffstat (limited to 'fs/ocfs2/mmap.c')
-rw-r--r--fs/ocfs2/mmap.c53
1 files changed, 24 insertions, 29 deletions
diff --git a/fs/ocfs2/mmap.c b/fs/ocfs2/mmap.c
index 3e9393ca39e..9cd41083e99 100644
--- a/fs/ocfs2/mmap.c
+++ b/fs/ocfs2/mmap.c
@@ -61,7 +61,7 @@ static int ocfs2_fault(struct vm_area_struct *area, struct vm_fault *vmf)
static int __ocfs2_page_mkwrite(struct file *file, struct buffer_head *di_bh,
struct page *page)
{
- int ret;
+ int ret = VM_FAULT_NOPAGE;
struct inode *inode = file->f_path.dentry->d_inode;
struct address_space *mapping = inode->i_mapping;
loff_t pos = page_offset(page);
@@ -71,32 +71,25 @@ static int __ocfs2_page_mkwrite(struct file *file, struct buffer_head *di_bh,
void *fsdata;
loff_t size = i_size_read(inode);
- /*
- * Another node might have truncated while we were waiting on
- * cluster locks.
- * We don't check size == 0 before the shift. This is borrowed
- * from do_generic_file_read.
- */
last_index = (size - 1) >> PAGE_CACHE_SHIFT;
- if (unlikely(!size || page->index > last_index)) {
- ret = -EINVAL;
- goto out;
- }
/*
- * The i_size check above doesn't catch the case where nodes
- * truncated and then re-extended the file. We'll re-check the
- * page mapping after taking the page lock inside of
- * ocfs2_write_begin_nolock().
+ * There are cases that lead to the page no longer bebongs to the
+ * mapping.
+ * 1) pagecache truncates locally due to memory pressure.
+ * 2) pagecache truncates when another is taking EX lock against
+ * inode lock. see ocfs2_data_convert_worker.
+ *
+ * The i_size check doesn't catch the case where nodes truncated and
+ * then re-extended the file. We'll re-check the page mapping after
+ * taking the page lock inside of ocfs2_write_begin_nolock().
+ *
+ * Let VM retry with these cases.
*/
- if (!PageUptodate(page) || page->mapping != inode->i_mapping) {
- /*
- * the page has been umapped in ocfs2_data_downconvert_worker.
- * So return 0 here and let VFS retry.
- */
- ret = 0;
+ if ((page->mapping != inode->i_mapping) ||
+ (!PageUptodate(page)) ||
+ (page_offset(page) >= size))
goto out;
- }
/*
* Call ocfs2_write_begin() and ocfs2_write_end() to take
@@ -116,17 +109,21 @@ static int __ocfs2_page_mkwrite(struct file *file, struct buffer_head *di_bh,
if (ret) {
if (ret != -ENOSPC)
mlog_errno(ret);
+ if (ret == -ENOMEM)
+ ret = VM_FAULT_OOM;
+ else
+ ret = VM_FAULT_SIGBUS;
goto out;
}
- ret = ocfs2_write_end_nolock(mapping, pos, len, len, locked_page,
- fsdata);
- if (ret < 0) {
- mlog_errno(ret);
+ if (!locked_page) {
+ ret = VM_FAULT_NOPAGE;
goto out;
}
+ ret = ocfs2_write_end_nolock(mapping, pos, len, len, locked_page,
+ fsdata);
BUG_ON(ret != len);
- ret = 0;
+ ret = VM_FAULT_LOCKED;
out:
return ret;
}
@@ -168,8 +165,6 @@ static int ocfs2_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
out:
ocfs2_unblock_signals(&oldset);
- if (ret)
- ret = VM_FAULT_SIGBUS;
return ret;
}