linux/fs/seq_file.c, branch v5.9

treewide: Use fallthrough pseudo-keyword

2020-08-23T22:36:59Z

Replace the existing /* fall through */ comments and its variants with the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary fall-through markings when it is the case. [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through Signed-off-by: Gustavo A. R. Silva

fs/seq_file.c: seq_read: Update pr_info_ratelimited

2020-06-05T02:06:25Z

Use a more common logging style. Add and use pr_fmt, coalesce the format string, align arguments, use better grammar. Signed-off-by: Joe Perches Signed-off-by: Andrew Morton Cc: Vasily Averin Link: http://lkml.kernel.org/r/96ff603230ca1bd60034c36519be3930c3a3a226.camel@perches.com Signed-off-by: Linus Torvalds

fs/seq_file.c: seq_read(): add info message about buggy .next functions

2020-04-10T22:36:22Z

Patch series "seq_file .next functions should increase position index". In Aug 2018 NeilBrown noticed commit 1f4aace60b0e ("fs/seq_file.c: simplify seq_file iteration code and interface") "Some ->next functions do not increment *pos when they return NULL... Note that such ->next functions are buggy and should be fixed. A simple demonstration is dd if=/proc/swaps bs=1000 skip=1 Choose any block size larger than the size of /proc/swaps. This will always show the whole last line of /proc/swaps" Described problem is still actual. If you make lseek into middle of last output line following read will output end of last line and whole last line once again. $ dd if=/proc/swaps bs=1 # usual output Filename Type Size Used Priority /dev/dm-0 partition 4194812 97536 -2 104+0 records in 104+0 records out 104 bytes copied $ dd if=/proc/swaps bs=40 skip=1 # last line was generated twice dd: /proc/swaps: cannot skip to specified offset v/dm-0 partition 4194812 97536 -2 /dev/dm-0 partition 4194812 97536 -2 3+1 records in 3+1 records out 131 bytes copied There are lot of other affected files, I've found 30+ including /proc/net/ip_tables_matches and /proc/sysvipc/* I've sent patches into maillists of affected subsystems already, this patch-set fixes the problem in files related to pstore, tracing, gcov, sysvipc and other subsystems processed via linux-kernel@ mailing list directly https://bugzilla.kernel.org/show_bug.cgi?id=206283 This patch (of 4): Add debug code to seq_read() to detect missed or out-of-tree incorrect .next seq_file functions. [akpm@linux-foundation.org: s/pr_info/pr_info_ratelimited/, per Qian Cai] https://bugzilla.kernel.org/show_bug.cgi?id=206283 Signed-off-by: Vasily Averin Signed-off-by: Andrew Morton Cc: NeilBrown Cc: Al Viro Cc: Steven Rostedt Cc: Davidlohr Bueso Cc: Ingo Molnar Cc: Manfred Spraul Cc: Peter Oberparleiter Cc: Waiman Long Link: http://lkml.kernel.org/r/244674e5-760c-86bd-d08a-047042881748@virtuozzo.com Link: http://lkml.kernel.org/r/7c24087c-e280-e580-5b0c-0cdaeb14cd18@virtuozzo.com Signed-off-by: Linus Torvalds

seq_file: remove m->version

2020-04-07T17:43:42Z

The process maps file was the only user of version (introduced back in 2005). Now that it uses ppos instead, we can remove it. Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Alexey Dobriyan Signed-off-by: Andrew Morton Link: http://lkml.kernel.org/r/20200317193201.9924-4-adobriyan@gmail.com Signed-off-by: Linus Torvalds

seq_file: fix problem when seeking mid-record

2019-08-13T23:06:52Z

If you use lseek or similar (e.g. pread) to access a location in a seq_file file that is within a record, rather than at a record boundary, then the first read will return the remainder of the record, and the second read will return the whole of that same record (instead of the next record). When seeking to a record boundary, the next record is correctly returned. This bug was introduced by a recent patch (identified below). Before that patch, seq_read() would increment m->index when the last of the buffer was returned (m->count == 0). After that patch, we rely on ->next to increment m->index after filling the buffer - but there was one place where that didn't happen. Link: https://lkml.kernel.org/lkml/877e7xl029.fsf@notabene.neil.brown.name/ Fixes: 1f4aace60b0e ("fs/seq_file.c: simplify seq_file iteration code and interface") Signed-off-by: NeilBrown Reported-by: Sergei Turchanov Tested-by: Sergei Turchanov Cc: Alexander Viro Cc: Markus Elfring Cc: [4.19+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

nfsd: escape high characters in binary data

2019-07-03T21:52:50Z

I'm exposing some information about NFS clients in pseudofiles. I expect to eventually have simple tools to help read those pseudofiles. But it's also helpful if the raw files are human-readable to the extent possible. It aids debugging and makes them usable on systems that don't have the latest nfs-utils. A minor challenge there is opaque client-generated protocol objects like state owners and client identifiers. Some clients generate those to include handy information in plain ascii. But they may also include arbitrary byte sequences. I think the simplest approach is to limit to isprint(c) && isascii(c) and escape everything else. That means you can just cat the file and get something that looks OK. Also, I'm trying to keep these files legal YAML, which requires them to UTF-8, and this is a simple way to guarantee that. Acked-by: Kees Cook Signed-off-by: J. Bruce Fields

fs: mark expected switch fall-throughs

2019-04-08T23:21:02Z

In preparation to enabling -Wimplicit-fallthrough, mark switch cases where we are expecting to fall through. This patch fixes the following warnings: fs/affs/affs.h:124:38: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/configfs/dir.c:1692:11: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/configfs/dir.c:1694:7: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/ceph/file.c:249:3: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/ext4/hash.c:233:15: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/ext4/hash.c:246:15: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/ext2/inode.c:1237:7: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/ext2/inode.c:1244:7: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/ext4/indirect.c:1182:6: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/ext4/indirect.c:1188:6: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/ext4/indirect.c:1432:6: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/ext4/indirect.c:1440:6: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/f2fs/node.c:618:8: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/f2fs/node.c:620:8: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/btrfs/ref-verify.c:522:15: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/gfs2/bmap.c:711:7: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/gfs2/bmap.c:722:7: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/jffs2/fs.c:339:6: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/nfsd/nfs4proc.c:429:12: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/ufs/util.h:62:6: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/ufs/util.h:43:6: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/fcntl.c:770:7: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/seq_file.c:319:10: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/libfs.c:148:11: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/libfs.c:150:7: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/signalfd.c:178:7: warning: this statement may fall through [-Wimplicit-fallthrough=] fs/locks.c:1473:16: warning: this statement may fall through [-Wimplicit-fallthrough=] Warning level 3 was used: -Wimplicit-fallthrough=3 This patch is part of the ongoing efforts to enabling -Wimplicit-fallthrough. Reviewed-by: Kees Cook Signed-off-by: Gustavo A. R. Silva

fs/seq_file.c: simplify seq_file iteration code and interface

2018-08-17T23:20:28Z

The documentation for seq_file suggests that it is necessary to be able to move the iterator to a given offset, however that is not the case. If the iterator is stored in the private data and is stable from one read() syscall to the next, it is only necessary to support first/next interactions. Implementing this in a client is a little clumsy. - if ->start() is given a pos of zero, it should go to start of sequence. - if ->start() is given the name pos that was given to the most recent next() or start(), it should restore the iterator to state just before that last call - if ->start is given another number, it should set the iterator one beyond the start just before the last ->start or ->next call. Also, the documentation says that the implementation can interpret the pos however it likes (other than zero meaning start), but seq_file increments the pos sometimes which does impose on the implementation. This patch simplifies the interface for first/next iteration and simplifies the code, while maintaining complete backward compatability. Now: - if ->start() is given a pos of zero, it should return an iterator placed at the start of the sequence - if ->start() is given a non-zero pos, it should return the iterator in the same state it was after the last ->start or ->next. This is particularly useful for interators which walk the multiple chains in a hash table, e.g. using rhashtable_walk*. See fs/gfs2/glock.c and drivers/staging/lustre/lustre/llite/vvp_dev.c A large part of achieving this is to *always* call ->next after ->show has successfully stored all of an entry in the buffer. Never just increment the index instead. Also: - always pass &m->index to ->start() and ->next(), never a temp variable - don't clear ->from when ->count is zero, as ->from is dead when ->count is zero. Some ->next functions do not increment *pos when they return NULL. To maintain compatability with this, we still need to increment m->index in one place, if ->next didn't increment it. Note that such ->next functions are buggy and should be fixed. A simple demonstration is dd if=/proc/swaps bs=1000 skip=1 Choose any block size larger than the size of /proc/swaps. This will always show the whole last line of /proc/swaps. This patch doesn't work around buggy next() functions for this case. [neilb@suse.com: ensure ->from is valid] Link: http://lkml.kernel.org/r/87601ryb8a.fsf@notabene.neil.brown.name Signed-off-by: NeilBrown Acked-by: Jonathan Corbet [docs] Tested-by: Jann Horn Cc: Alexander Viro Cc: Kees Cook Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

proc: fix smaps and meminfo alignment

2018-05-26T01:12:11Z

The 4.17-rc /proc/meminfo and /proc//smaps look ugly: single-digit numbers (commonly 0) are misaligned. Remove seq_put_decimal_ull_width()'s leftover optimization for single digits: it's wrong now that num_to_str() takes care of the width. Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1805241554210.1326@eggly.anvils Fixes: d1be35cb6f96 ("proc: add seq_put_decimal_ull_width to speed up /proc/pid/smaps") Signed-off-by: Hugh Dickins Cc: Andrei Vagin Cc: Alexey Dobriyan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

seq_file: account everything to kmemcg

2018-04-11T17:28:36Z

All it takes to open a file and read 1 byte from it. seq_file will be allocated along with any private allocations, and more importantly seq file buffer which is 1 page by default. Link: http://lkml.kernel.org/r/20180310085252.GB17121@avx2 Signed-off-by: Alexey Dobriyan Reviewed-by: Andrew Morton Acked-by: Michal Hocko Cc: Al Viro Cc: Glauber Costa Cc: Vladimir Davydov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds