ceph: use i_size_{read,write} to get/set i_size

Cap message from MDS can update i_size. In that case, we don't
hold i_mutex. So it's unsafe to directly access inode->i_size
while holding i_mutex.

Signed-off-by: Yan, Zheng <zyan@redhat.com>

1 files changed, 16 insertions, 14 deletions

diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index 41c2267b4b7e..d37efdd8533d 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -417,6 +417,7 @@ static int striped_read(struct inode *inode,
         struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
         struct ceph_inode_info *ci = ceph_inode(inode);
         u64 pos, this_len, left;
+        loff_t i_size;
         int page_align, pages_left;
         int read, ret;
         struct page **page_pos;
@@ -446,11 +447,11 @@ more:
         dout("striped_read %llu~%llu (read %u) got %d%s%s\n", pos, left, read,
              ret, hit_stripe ? " HITSTRIPE" : "", was_short ? " SHORT" : "");
 
+        i_size = i_size_read(inode);
         if (ret >= 0) {
                 int didpages;
-                if (was_short && (pos + ret < inode->i_size)) {
-                        int zlen = min(this_len - ret,
-                                       inode->i_size - pos - ret);
+                if (was_short && (pos + ret < i_size)) {
+                        int zlen = min(this_len - ret, i_size - pos - ret);
                         int zoff = (off & ~PAGE_MASK) + read + ret;
                         dout(" zero gap %llu to %llu\n",
                                 pos + ret, pos + ret + zlen);
@@ -466,14 +467,14 @@ more:
                 pages_left -= didpages;
 
                 /* hit stripe and need continue*/
-                if (left && hit_stripe && pos < inode->i_size)
+                if (left && hit_stripe && pos < i_size)
                         goto more;
         }
 
         if (read > 0) {
                 ret = read;
                 /* did we bounce off eof? */
-                if (pos + left > inode->i_size)
+                if (pos + left > i_size)
                         *checkeof = CHECK_EOF;
         }
 
@@ -1209,8 +1210,7 @@ again:
                 if (retry_op == CHECK_EOF && iocb->ki_pos < i_size &&
                     ret < len) {
                         dout("sync_read hit hole, ppos %lld < size %lld"
-                             ", reading more\n", iocb->ki_pos,
-                             inode->i_size);
+                             ", reading more\n", iocb->ki_pos, i_size);
 
                         read += ret;
                         len -= ret;
@@ -1293,7 +1293,7 @@ retry_snap:
         }
 
         dout("aio_write %p %llx.%llx %llu~%zd getting caps. i_size %llu\n",
-             inode, ceph_vinop(inode), pos, count, inode->i_size);
+             inode, ceph_vinop(inode), pos, count, i_size_read(inode));
         if (fi->fmode & CEPH_FILE_MODE_LAZY)
                 want = CEPH_CAP_FILE_BUFFER | CEPH_CAP_FILE_LAZYIO;
         else
@@ -1345,7 +1345,7 @@ retry_snap:
                         iov_iter_advance(from, written);
                 ceph_put_snap_context(snapc);
         } else {
-                loff_t old_size = inode->i_size;
+                loff_t old_size = i_size_read(inode);
                 /*
                  * No need to acquire the i_truncate_mutex. Because
                  * the MDS revokes Fwb caps before sending truncate
@@ -1356,7 +1356,7 @@ retry_snap:
                 written = generic_perform_write(file, from, pos);
                 if (likely(written >= 0))
                         iocb->ki_pos = pos + written;
-                if (inode->i_size > old_size)
+                if (i_size_read(inode) > old_size)
                         ceph_fscache_update_objectsize(inode);
                 mutex_unlock(&inode->i_mutex);
         }
@@ -1401,6 +1401,7 @@ out_unlocked:
 static loff_t ceph_llseek(struct file *file, loff_t offset, int whence)
 {
         struct inode *inode = file->f_mapping->host;
+        loff_t i_size;
         int ret;
 
         mutex_lock(&inode->i_mutex);
@@ -1413,9 +1414,10 @@ static loff_t ceph_llseek(struct file *file, loff_t offset, int whence)
                 }
         }
 
+        i_size = i_size_read(inode);
         switch (whence) {
         case SEEK_END:
-                offset += inode->i_size;
+                offset += i_size;
                 break;
         case SEEK_CUR:
                 /*
@@ -1431,17 +1433,17 @@ static loff_t ceph_llseek(struct file *file, loff_t offset, int whence)
                 offset += file->f_pos;
                 break;
         case SEEK_DATA:
-                if (offset >= inode->i_size) {
+                if (offset >= i_size) {
                         ret = -ENXIO;
                         goto out;
                 }
                 break;
         case SEEK_HOLE:
-                if (offset >= inode->i_size) {
+                if (offset >= i_size) {
                         ret = -ENXIO;
                         goto out;
                 }
-                offset = inode->i_size;
+                offset = i_size;
                 break;
         }