After the BKL removal patches were applied to the rest of the NFS code, the
BKL protection in nfs_file_llseek() is no longer sufficient to ensure that
inode->i_size is read safely in generic_file_llseek_unlocked().
In order to fix the situation, we either have to replace the naked read of
inode->i_size in generic_file_llseek_unlocked() with i_size_read(), or the
whole thing needs to be executed under the inode->i_lock;
In order to avoid disrupting other filesystems, avoid touching
generic_file_llseek_unlocked() for now...
Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
---
fs/nfs/file.c | 11 +++++++----
1 files changed, 7 insertions(+), 4 deletions(-)
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 7846065..3ddb004 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -188,13 +188,16 @@ static loff_t nfs_file_llseek(struct file *filp, loff_t offset, int origin)
/* origin == SEEK_END => we must revalidate the cached file length */
if (origin == SEEK_END) {
struct inode *inode = filp->f_mapping->host;
+
int retval = nfs_revalidate_file_size(inode, filp);
if (retval < 0)
return (loff_t)retval;
- }
- lock_kernel(); /* BKL needed? */
- loff = generic_file_llseek_unlocked(filp, offset, origin);
- unlock_kernel();
+
+ spin_lock(&inode->i_lock);
+ loff = generic_file_llseek_unlocked(filp, offset, origin);
+ spin_unlock(&inode->i_lock);
+ } else
+ loff = generic_file_llseek_unlocked(filp, offset, origin);
return loff;
}
--
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