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Subject[20/40] udf: Fix deadlock when converting file from in-ICB one to normal one
3.0-stable review patch.  If anyone has any objections, please let me know.

------------------
From: Jan Kara <jack@suse.cz>

commit d2eb8c359309ec45d6bf5b147303ab8e13be86ea upstream.

During BKL removal in 2.6.38, conversion of files from in-ICB format to normal
format got broken. We call ->writepage with i_data_sem held but udf_get_block()
also acquires i_data_sem thus creating A-A deadlock.

We fix the problem by dropping i_data_sem before calling ->writepage() which is
safe since i_mutex still protects us against any changes in the file. Also fix
pagelock - i_data_sem lock inversion in udf_expand_file_adinicb() by dropping
i_data_sem before calling find_or_create_page().

Reported-by: Matthias Matiak <netzpython@mail-on.us>
Tested-by: Matthias Matiak <netzpython@mail-on.us>
Reviewed-by: Namjae Jeon <linkinjeon@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
fs/udf/file.c | 6 +++---
fs/udf/inode.c | 21 ++++++++++++++++++---
2 files changed, 21 insertions(+), 6 deletions(-)
--- a/fs/udf/file.c
+++ b/fs/udf/file.c
@@ -125,7 +125,6 @@ static ssize_t udf_file_aio_write(struct
err = udf_expand_file_adinicb(inode);
if (err) {
udf_debug("udf_expand_adinicb: err=%d\n", err);
- up_write(&iinfo->i_data_sem);
return err;
}
} else {
@@ -133,9 +132,10 @@ static ssize_t udf_file_aio_write(struct
iinfo->i_lenAlloc = pos + count;
else
iinfo->i_lenAlloc = inode->i_size;
+ up_write(&iinfo->i_data_sem);
}
- }
- up_write(&iinfo->i_data_sem);
+ } else
+ up_write(&iinfo->i_data_sem);

retval = generic_file_aio_write(iocb, iov, nr_segs, ppos);
if (retval > 0)
--- a/fs/udf/inode.c
+++ b/fs/udf/inode.c
@@ -145,6 +145,12 @@ const struct address_space_operations ud
.bmap = udf_bmap,
};

+/*
+ * Expand file stored in ICB to a normal one-block-file
+ *
+ * This function requires i_data_sem for writing and releases it.
+ * This function requires i_mutex held
+ */
int udf_expand_file_adinicb(struct inode *inode)
{
struct page *page;
@@ -163,9 +169,15 @@ int udf_expand_file_adinicb(struct inode
iinfo->i_alloc_type = ICBTAG_FLAG_AD_LONG;
/* from now on we have normal address_space methods */
inode->i_data.a_ops = &udf_aops;
+ up_write(&iinfo->i_data_sem);
mark_inode_dirty(inode);
return 0;
}
+ /*
+ * Release i_data_sem so that we can lock a page - page lock ranks
+ * above i_data_sem. i_mutex still protects us against file changes.
+ */
+ up_write(&iinfo->i_data_sem);

page = find_or_create_page(inode->i_mapping, 0, GFP_NOFS);
if (!page)
@@ -181,6 +193,7 @@ int udf_expand_file_adinicb(struct inode
SetPageUptodate(page);
kunmap(page);
}
+ down_write(&iinfo->i_data_sem);
memset(iinfo->i_ext.i_data + iinfo->i_lenEAttr, 0x00,
iinfo->i_lenAlloc);
iinfo->i_lenAlloc = 0;
@@ -190,17 +203,20 @@ int udf_expand_file_adinicb(struct inode
iinfo->i_alloc_type = ICBTAG_FLAG_AD_LONG;
/* from now on we have normal address_space methods */
inode->i_data.a_ops = &udf_aops;
+ up_write(&iinfo->i_data_sem);
err = inode->i_data.a_ops->writepage(page, &udf_wbc);
if (err) {
/* Restore everything back so that we don't lose data... */
lock_page(page);
kaddr = kmap(page);
+ down_write(&iinfo->i_data_sem);
memcpy(iinfo->i_ext.i_data + iinfo->i_lenEAttr, kaddr,
inode->i_size);
kunmap(page);
unlock_page(page);
iinfo->i_alloc_type = ICBTAG_FLAG_AD_IN_ICB;
inode->i_data.a_ops = &udf_adinicb_aops;
+ up_write(&iinfo->i_data_sem);
}
page_cache_release(page);
mark_inode_dirty(inode);
@@ -1105,10 +1121,9 @@ int udf_setsize(struct inode *inode, lof
if (bsize <
(udf_file_entry_alloc_offset(inode) + newsize)) {
err = udf_expand_file_adinicb(inode);
- if (err) {
- up_write(&iinfo->i_data_sem);
+ if (err)
return err;
- }
+ down_write(&iinfo->i_data_sem);
} else
iinfo->i_lenAlloc = newsize;
}



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