On 02.12.21 11:48, Holger Assmann wrote: > This bug resulted in a panic when trying to read a file partially with > an offset, e.g. when starting Linux. In such a case a header is loaded > by a separate call of jffs2_read(), which then copies only the first n > bytes out of the respective block. > When the remaining data of the block is then subsequently going to to be > read the system deviates in its behaviour from that under Linux by not > calling jffs2_read_inode_range() in a 4k-alignment, but with an offset. > > jffs2_read_inode_range() originates from the Linux jffs2 driver. When > being called with an offset it still reads 4096 bytes of data and > eventually returns fragments of two consecutive blocks. jffs2_read() > then reads this result whilst again applying the offset, therefore > returning faulty data. > > We fix that problem by calling jffs2_get_block() without an offset and > therefore reading the whole block. The offset is then applied when we > actually perform memcpy with the returned buffer. This fix might also > increase the performance since the respective block is likely to be > cached from the previous call. > > Signed-off-by: Holger Assmann <[email protected]> > --- > fs/jffs2/fs.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/fs/jffs2/fs.c b/fs/jffs2/fs.c > index 1a2b443792..3d4cb98c97 100644 > --- a/fs/jffs2/fs.c > +++ b/fs/jffs2/fs.c > @@ -74,6 +74,9 @@ static int jffs2_get_block(struct jffs2_file *jf, unsigned > int pos) > struct jffs2_inode_info *f = JFFS2_INODE_INFO(jf->inode); > int ret; > > + /* pos always has to be 4096 bytes aligned here */ > + WARN_ON(pos % 4096 != 0); > + > if (pos != jf->offset) { > ret = jffs2_read_inode_range(c, f, jf->buf, pos, > JFFS2_BLOCK_SIZE); > @@ -98,13 +101,14 @@ static int jffs2_read(struct device_d *_dev, FILE *f, > void *buf, > /* Read till end of current block */ > ofs = f->pos % JFFS2_BLOCK_SIZE; > if (ofs) { > - ret = jffs2_get_block(jf, pos); > + ret = jffs2_get_block(jf, f->pos - ofs); /* Align down block */ > if (ret) > return ret; > > now = min(size, JFFS2_BLOCK_SIZE - ofs); > > - memcpy(buf, jf->buf + ofs, now); > + /* Complete block has been read, re-apply ofset now */ > + memcpy(buf, jf->buf + ofs, now);
Newly added stray space at end of line. Apart from that: Reviewed-by: Ahmad Fatoum <[email protected]> > size -= now; > pos += now; > buf += now; > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list [email protected] http://lists.infradead.org/mailman/listinfo/barebox
