From patchwork Mon Dec 1 12:48:22 2008 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: Problems with JFFS2 FS during parallel write operations Date: Mon, 01 Dec 2008 02:48:22 -0000 From: Geert Uytterhoeven X-Patchwork-Id: 11571 Message-Id: To: "Ostendorf, Rainer" Cc: linux-mtd@lists.infradead.org On Mon, 1 Dec 2008, Ostendorf, Rainer wrote: > i'm still working on the problem described in my previous post: > > [...] > > During normal operation the system runs perfectly stable, but when i > > start two processes running parallel, writing huge amounts of data > > to the flash device, i get error > > messages from the JFFS2 filesystem: > > > > ... > > argh. node added in wrong place > > argh. node added in wrong place > > ... > > > > This message repeats for about 15-20 times while copying parallel 2 > > files of about 6MByte to the flash via Ethernet (SCP). > [...] > > As i can only reproduce the corruption of the JFFS2 FS during parallel access of at leat two processes writing to the flash, i assume that the cause for the corruption is some kind of race-condition. Have there been any known problems/bugs with race conditions, that could lead to an error like this? Would it probably help to upgrade to a newer kernel version? Any hint and help would be greatly appreciated. Do you use LZO compression? If yes, it could have been this one: commit dc8a0843a435b2c0891e7eaea64faaf1ebec9b11 Author: Geert Uytterhoeven Date: Wed Nov 5 23:21:16 2008 +0100 [JFFS2] fix race condition in jffs2_lzo_compress() deflate_mutex protects the globals lzo_mem and lzo_compress_buf. However, jffs2_lzo_compress() unlocks deflate_mutex _before_ it has copied out the compressed data from lzo_compress_buf. Correct this by moving the mutex unlock after the copy. In addition, document what deflate_mutex actually protects. Cc: stable@kernel.org Signed-off-by: Geert Uytterhoeven Acked-by: Richard Purdie Signed-off-by: Andrew Morton Signed-off-by: David Woodhouse With kind regards, Geert Uytterhoeven Software Architect Sony Techsoft Centre Europe The Corporate Village · Da Vincilaan 7-D1 · B-1935 Zaventem · Belgium Phone: +32 (0)2 700 8453 Fax: +32 (0)2 700 8622 E-mail: Geert.Uytterhoeven@sonycom.com Internet: http://www.sony-europe.com/ A division of Sony Europe (Belgium) N.V. VAT BE 0413.825.160 · RPR Brussels Fortis · BIC GEBABEBB · IBAN BE41293037680010 diff --git a/fs/jffs2/compr_lzo.c b/fs/jffs2/compr_lzo.c index 47b0457..90cb60d 100644 --- a/fs/jffs2/compr_lzo.c +++ b/fs/jffs2/compr_lzo.c @@ -19,7 +19,7 @@ static void *lzo_mem; static void *lzo_compress_buf; -static DEFINE_MUTEX(deflate_mutex); +static DEFINE_MUTEX(deflate_mutex); /* for lzo_mem and lzo_compress_buf */ static void free_workspace(void) { @@ -49,18 +49,21 @@ static int jffs2_lzo_compress(unsigned char *data_in, unsigned char *cpage_out, mutex_lock(&deflate_mutex); ret = lzo1x_1_compress(data_in, *sourcelen, lzo_compress_buf, &compress_size, lzo_mem); - mutex_unlock(&deflate_mutex); - if (ret != LZO_E_OK) - return -1; + goto fail; if (compress_size > *dstlen) - return -1; + goto fail; memcpy(cpage_out, lzo_compress_buf, compress_size); - *dstlen = compress_size; + mutex_unlock(&deflate_mutex); + *dstlen = compress_size; return 0; + + fail: + mutex_unlock(&deflate_mutex); + return -1; } static int jffs2_lzo_decompress(unsigned char *data_in, unsigned char *cpage_out,