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Subject[PATCH V1 03/17] ext4: Add read support for inline data.
Date
From: Tao Ma <boyu.mt@taobao.com>

Let readpage and readpages handle the case when we
want to read an inlined file.

Signed-off-by: Tao Ma <boyu.mt@taobao.comc.
---
fs/ext4/inode.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 68 insertions(+), 0 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 017e119..2fa8cf4 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -540,6 +540,9 @@ static int _ext4_get_block(struct inode *inode, sector_t iblock,
int ret = 0, started = 0;
int dio_credits;

+ if (ext4_has_inline_data(inode))
+ return -ERANGE;
+
map.m_lblk = iblock;
map.m_len = bh->b_size >> inode->i_blkbits;

@@ -2483,6 +2486,12 @@ static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
journal_t *journal;
int err;

+ /*
+ * XXX: Can we arrive here for a inline file? Maybe not.
+ */
+ if (ext4_has_inline_data(inode))
+ return 0;
+
if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
test_opt(inode->i_sb, DELALLOC)) {
/*
@@ -2526,9 +2535,58 @@ static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
return generic_block_bmap(mapping, block, ext4_get_block);
}

+static int ext4_read_inline_page(struct inode *inode, struct page *page)
+{
+ void *kaddr;
+ loff_t size;
+ int ret;
+ struct ext4_iloc iloc;
+
+ BUG_ON(!PageLocked(page));
+ BUG_ON(!ext4_has_inline_data(inode));
+
+ ret = ext4_get_inode_loc(inode, &iloc);
+ if (ret)
+ return ret;
+
+ size = i_size_read(inode);
+
+ if (size > PAGE_CACHE_SIZE ||
+ size > ext4_get_max_inline_size(inode)) {
+ ext4_error_inode(inode, __func__, __LINE__, 0,
+ "bad size %ld for a inline file", (long)size);
+ return -EROFS;
+ }
+
+ kaddr = kmap_atomic(page, KM_USER0);
+ ext4_read_inline_data(inode, &iloc, kaddr, size);
+ flush_dcache_page(page);
+ kunmap_atomic(kaddr, KM_USER0);
+ SetPageUptodate(page);
+
+ brelse(iloc.bh);
+ return 0;
+}
+
+static int ext4_readpage_inline(struct inode *inode, struct page *page)
+{
+ int ret;
+
+ ret = ext4_read_inline_page(inode, page);
+
+ unlock_page(page);
+ return ret;
+}
+
static int ext4_readpage(struct file *file, struct page *page)
{
+ struct inode *inode = file->f_mapping->host;
+
trace_ext4_readpage(page);
+
+ if (ext4_has_inline_data(inode))
+ return ext4_readpage_inline(inode, page);
+
return mpage_readpage(page, ext4_get_block);
}

@@ -2536,6 +2594,12 @@ static int
ext4_readpages(struct file *file, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages)
{
+ struct inode *inode = mapping->host;
+
+ /* If the file has inline data, no need to do readpages. */
+ if (ext4_has_inline_data(inode))
+ return 0;
+
return mpage_readpages(mapping, pages, nr_pages, ext4_get_block);
}

@@ -2854,6 +2918,10 @@ static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,
struct inode *inode = file->f_mapping->host;
ssize_t ret;

+ /* Let buffer I/O handle the inline data case. */
+ if (ext4_has_inline_data(inode))
+ return 0;
+
trace_ext4_direct_IO_enter(inode, offset, iov_length(iov, nr_segs), rw);
if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
ret = ext4_ext_direct_IO(rw, iocb, iov, offset, nr_segs);
--
1.7.0.4


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