5.4-stable review patch. If anyone has any objections, please let me know.
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From: Simon Tatham anakin@pobox.com
[ Upstream commit e4cf8ec4de4e13f156c1d61977d282d90c221085 ]
If I write a file to an OFS floppy image, and try to read it back on an emulated Amiga running Workbench 1.3, the Amiga reports a disk error trying to read the file. (That is, it's unable to read it _at all_, even to copy it to the NIL: device. It isn't a matter of getting the wrong data and being unable to parse the file format.)
This is because the 'sequence number' field in the OFS data block header is supposed to be based at 1, but affs writes it based at 0. All three locations changed by this patch were setting the sequence number to a variable 'bidx' which was previously obtained by dividing a file position by bsize, so bidx will naturally use 0 for the first block. Therefore all three should add 1 to that value before writing it into the sequence number field.
With this change, the Amiga successfully reads the file.
For data block reference: https://wiki.osdev.org/FFS_(Amiga)
Signed-off-by: Simon Tatham anakin@pobox.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/affs/file.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/fs/affs/file.c b/fs/affs/file.c index 82bb38370aa9a..6dae4ca09be5f 100644 --- a/fs/affs/file.c +++ b/fs/affs/file.c @@ -596,7 +596,7 @@ affs_extent_file_ofs(struct inode *inode, u32 newsize) BUG_ON(tmp > bsize); AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA); AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino); - AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx); + AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx + 1); AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp); affs_fix_checksum(sb, bh); bh->b_state &= ~(1UL << BH_New); @@ -746,7 +746,7 @@ static int affs_write_end_ofs(struct file *file, struct address_space *mapping, if (buffer_new(bh)) { AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA); AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino); - AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx); + AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx + 1); AFFS_DATA_HEAD(bh)->size = cpu_to_be32(bsize); AFFS_DATA_HEAD(bh)->next = 0; bh->b_state &= ~(1UL << BH_New); @@ -780,7 +780,7 @@ static int affs_write_end_ofs(struct file *file, struct address_space *mapping, if (buffer_new(bh)) { AFFS_DATA_HEAD(bh)->ptype = cpu_to_be32(T_DATA); AFFS_DATA_HEAD(bh)->key = cpu_to_be32(inode->i_ino); - AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx); + AFFS_DATA_HEAD(bh)->sequence = cpu_to_be32(bidx + 1); AFFS_DATA_HEAD(bh)->size = cpu_to_be32(tmp); AFFS_DATA_HEAD(bh)->next = 0; bh->b_state &= ~(1UL << BH_New);