unimore/kernel-hacking-2024-linux-steffo
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UDF: Add support for O_DIRECT

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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@mev.co.uk>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Ian Abbott 2012-09-05 17:44:31 +01:00 committed by Jan Kara
parent 3f6bba8237
commit 5eec54fcde
3 changed files with 45 additions and 16 deletions
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2
arch/um/os-Linux/time.c
View file

@ -114,7 +114,7 @@ static void deliver_alarm(void)
skew += this_tick - last_tick;
while (skew >= one_tick) {
alarm_handler(SIGVTALRM, NULL);
alarm_handler(SIGVTALRM, NULL, NULL);
skew -= one_tick;
}

9
fs/udf/file.c
View file

@ -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,

50
fs/udf/inode.c
View file

@ -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 (unlikely(ret))
udf_write_failed(mapping, pos + len);
return ret;
}
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);
}
}
}
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,
};