Add support for the O_DIRECT flag. There are two cases to deal with:
1. Small files stored in the ICB (inode control block?): just return 0
from the new udf_adinicb_direct_IO() handler to fall back to buffered
I/O.
2. Larger files, not stored in the ICB: nothing special here. Just call
blockdev_direct_IO() from our new udf_direct_IO() handler and tidy up
any blocks instantiated outside i_size on error. This is pretty
standard. Factor error handling code out of udf_write_begin() into new
function udf_write_failed() so it can also be called by udf_direct_IO().
Also change the whitespace in udf_aops to make it a bit neater.
Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
---
v2: Rework error handling in udf_direct_IO to avoid calling deprecated
vmtruncate().
v3: Rebased to next-20120904.
v4: Removed special handling in udf_adinicb_writepage() as that turned
out to be a bug in the handling of buffered writes for files in ICB,
fixed by Jan Kara's patch "udf: Fix data corruption for files in
ICB", dated 2012-09-05. I've tested it with that patch and it seems
to work without corrupting file data in the ICB.
---
fs/udf/file.c | 9 +++++++++
fs/udf/inode.c | 52 ++++++++++++++++++++++++++++++++++++----------------
2 files changed, 45 insertions(+), 16 deletions(-)
diff --git a/fs/udf/file.c b/fs/udf/file.c
index d1c6093..77b5953 100644
--- a/fs/udf/file.c
+++ b/fs/udf/file.c
@@ -118,11 +118,20 @@ static int udf_adinicb_write_end(struct file *file,
return simple_write_end(file, mapping, pos, len, copied, page, fsdata);
}
+static ssize_t udf_adinicb_direct_IO(int rw, struct kiocb *iocb,
+ const struct iovec *iov,
+ loff_t offset, unsigned long nr_segs)
+{
+ /* Fallback to buffered I/O. */
+ return 0;
+}
+
const struct address_space_operations udf_adinicb_aops = {
.readpage = udf_adinicb_readpage,
.writepage = udf_adinicb_writepage,
.write_begin = udf_adinicb_write_begin,
.write_end = udf_adinicb_write_end,
+ .direct_IO = udf_adinicb_direct_IO,
};
static ssize_t udf_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
diff --git a/fs/udf/inode.c b/fs/udf/inode.c
index 1a0588e..b905448 100644
--- a/fs/udf/inode.c
+++ b/fs/udf/inode.c
@@ -95,6 +95,22 @@ void udf_evict_inode(struct inode *inode)
}
}
+static void udf_write_failed(struct address_space *mapping, loff_t to)
+{
+ struct inode *inode = mapping->host;
+ struct udf_inode_info *iinfo = UDF_I(inode);
+ loff_t isize = inode->i_size;
+
+ if (to > isize) {
+ truncate_pagecache(inode, to, isize);
+ if (iinfo->i_alloc_type != ICBTAG_FLAG_AD_IN_ICB) {
+ down_write(&iinfo->i_data_sem);
+ udf_truncate_extents(inode);
+ up_write(&iinfo->i_data_sem);
+ }
+ }
+}
+
static int udf_writepage(struct page *page, struct writeback_control *wbc)
{
return block_write_full_page(page, udf_get_block, wbc);
@@ -124,21 +140,24 @@ static int udf_write_begin(struct file *file, struct address_space *mapping,
int ret;
ret = block_write_begin(mapping, pos, len, flags, pagep, udf_get_block);
- if (unlikely(ret)) {
- struct inode *inode = mapping->host;
- struct udf_inode_info *iinfo = UDF_I(inode);
- loff_t isize = inode->i_size;
-
- if (pos + len > isize) {
- truncate_pagecache(inode, pos + len, isize);
- if (iinfo->i_alloc_type != ICBTAG_FLAG_AD_IN_ICB) {
- down_write(&iinfo->i_data_sem);
- udf_truncate_extents(inode);
- up_write(&iinfo->i_data_sem);
- }
- }
- }
+ if (unlikely(ret))
+ udf_write_failed(mapping, pos + len);
+ return ret;
+}
+static ssize_t udf_direct_IO(int rw, struct kiocb *iocb,
+ const struct iovec *iov,
+ loff_t offset, unsigned long nr_segs)
+{
+ struct file *file = iocb->ki_filp;
+ struct address_space *mapping = file->f_mapping;
+ struct inode *inode = mapping->host;
+ ssize_t ret;
+
+ ret = blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
+ udf_get_block);
+ if (unlikely(ret < 0 && (rw && WRITE)))
+ udf_write_failed(mapping, offset + iov_length(iov, nr_segs));
return ret;
}
@@ -152,8 +171,9 @@ const struct address_space_operations udf_aops = {
.readpages = udf_readpages,
.writepage = udf_writepage,
.writepages = udf_writepages,
- .write_begin = udf_write_begin,
- .write_end = generic_write_end,
+ .write_begin = udf_write_begin,
+ .write_end = generic_write_end,
+ .direct_IO = udf_direct_IO,
.bmap = udf_bmap,
};
--
1.7.12
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