kernel.git/drivers/block/zram/zcomp.c, branch linux-4.7.y

zram: remove max_comp_streams internals

2016-05-21T00:58:30Z

Remove the internal part of max_comp_streams interface, since we switched to per-cpu streams. We will keep RW max_comp_streams attr around, because: a) we may (silently) switch back to idle compression streams list and don't want to disturb user space b) max_comp_streams attr must wait for the next 'lay off cycle'; we give user space 2 years to adjust before we remove/downgrade the attr, and there are already several attrs scheduled for removal in 4.11, so it's too late for max_comp_streams. This slightly change a user visible behaviour: - First, reading from max_comp_stream file now will always return the number of online CPUs. - Second, writing to max_comp_stream will not take any effect. Link: http://lkml.kernel.org/r/20160503165546.25201-1-sergey.senozhatsky@gmail.com Signed-off-by: Sergey Senozhatsky Cc: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

zram: user per-cpu compression streams

2016-05-21T00:58:30Z

Remove idle streams list and keep compression streams in per-cpu data. This removes two contented spin_lock()/spin_unlock() calls from write path and also prevent write OP from being preempted while holding the compression stream, which can cause slow downs. For instance, let's assume that we have N cpus and N-2 max_comp_streams.TASK1 owns the last idle stream, TASK2-TASK3 come in with the write requests: TASK1 TASK2 TASK3 zram_bvec_write() spin_lock find stream spin_unlock compress <> zram_bvec_write() spin_lock find stream spin_unlock no_stream schedule zram_bvec_write() spin_lock find_stream spin_unlock no_stream schedule spin_lock release stream spin_unlock wake up TASK2 not only TASK2 and TASK3 will not get the stream, TASK1 will be preempted in the middle of its operation; while we would prefer it to finish compression and release the stream. Test environment: x86_64, 4 CPU box, 3G zram, lzo The following fio tests were executed: read, randread, write, randwrite, rw, randrw with the increasing number of jobs from 1 to 10. 4 streams 8 streams per-cpu =========================================================== jobs1 READ: 2520.1MB/s 2566.5MB/s 2491.5MB/s READ: 2102.7MB/s 2104.2MB/s 2091.3MB/s WRITE: 1355.1MB/s 1320.2MB/s 1378.9MB/s WRITE: 1103.5MB/s 1097.2MB/s 1122.5MB/s READ: 434013KB/s 435153KB/s 439961KB/s WRITE: 433969KB/s 435109KB/s 439917KB/s READ: 403166KB/s 405139KB/s 403373KB/s WRITE: 403223KB/s 405197KB/s 403430KB/s jobs2 READ: 7958.6MB/s 8105.6MB/s 8073.7MB/s READ: 6864.9MB/s 6989.8MB/s 7021.8MB/s WRITE: 2438.1MB/s 2346.9MB/s 3400.2MB/s WRITE: 1994.2MB/s 1990.3MB/s 2941.2MB/s READ: 981504KB/s 973906KB/s 1018.8MB/s WRITE: 981659KB/s 974060KB/s 1018.1MB/s READ: 937021KB/s 938976KB/s 987250KB/s WRITE: 934878KB/s 936830KB/s 984993KB/s jobs3 READ: 13280MB/s 13553MB/s 13553MB/s READ: 11534MB/s 11785MB/s 11755MB/s WRITE: 3456.9MB/s 3469.9MB/s 4810.3MB/s WRITE: 3029.6MB/s 3031.6MB/s 4264.8MB/s READ: 1363.8MB/s 1362.6MB/s 1448.9MB/s WRITE: 1361.9MB/s 1360.7MB/s 1446.9MB/s READ: 1309.4MB/s 1310.6MB/s 1397.5MB/s WRITE: 1307.4MB/s 1308.5MB/s 1395.3MB/s jobs4 READ: 20244MB/s 20177MB/s 20344MB/s READ: 17886MB/s 17913MB/s 17835MB/s WRITE: 4071.6MB/s 4046.1MB/s 6370.2MB/s WRITE: 3608.9MB/s 3576.3MB/s 5785.4MB/s READ: 1824.3MB/s 1821.6MB/s 1997.5MB/s WRITE: 1819.8MB/s 1817.4MB/s 1992.5MB/s READ: 1765.7MB/s 1768.3MB/s 1937.3MB/s WRITE: 1767.5MB/s 1769.1MB/s 1939.2MB/s jobs5 READ: 18663MB/s 18986MB/s 18823MB/s READ: 16659MB/s 16605MB/s 16954MB/s WRITE: 3912.4MB/s 3888.7MB/s 6126.9MB/s WRITE: 3506.4MB/s 3442.5MB/s 5519.3MB/s READ: 1798.2MB/s 1746.5MB/s 1935.8MB/s WRITE: 1792.7MB/s 1740.7MB/s 1929.1MB/s READ: 1727.6MB/s 1658.2MB/s 1917.3MB/s WRITE: 1726.5MB/s 1657.2MB/s 1916.6MB/s jobs6 READ: 21017MB/s 20922MB/s 21162MB/s READ: 19022MB/s 19140MB/s 18770MB/s WRITE: 3968.2MB/s 4037.7MB/s 6620.8MB/s WRITE: 3643.5MB/s 3590.2MB/s 6027.5MB/s READ: 1871.8MB/s 1880.5MB/s 2049.9MB/s WRITE: 1867.8MB/s 1877.2MB/s 2046.2MB/s READ: 1755.8MB/s 1710.3MB/s 1964.7MB/s WRITE: 1750.5MB/s 1705.9MB/s 1958.8MB/s jobs7 READ: 21103MB/s 20677MB/s 21482MB/s READ: 18522MB/s 18379MB/s 19443MB/s WRITE: 4022.5MB/s 4067.4MB/s 6755.9MB/s WRITE: 3691.7MB/s 3695.5MB/s 5925.6MB/s READ: 1841.5MB/s 1933.9MB/s 2090.5MB/s WRITE: 1842.7MB/s 1935.3MB/s 2091.9MB/s READ: 1832.4MB/s 1856.4MB/s 1971.5MB/s WRITE: 1822.3MB/s 1846.2MB/s 1960.6MB/s jobs8 READ: 20463MB/s 20194MB/s 20862MB/s READ: 18178MB/s 17978MB/s 18299MB/s WRITE: 4085.9MB/s 4060.2MB/s 7023.8MB/s WRITE: 3776.3MB/s 3737.9MB/s 6278.2MB/s READ: 1957.6MB/s 1944.4MB/s 2109.5MB/s WRITE: 1959.2MB/s 1946.2MB/s 2111.4MB/s READ: 1900.6MB/s 1885.7MB/s 2082.1MB/s WRITE: 1896.2MB/s 1881.4MB/s 2078.3MB/s jobs9 READ: 19692MB/s 19734MB/s 19334MB/s READ: 17678MB/s 18249MB/s 17666MB/s WRITE: 4004.7MB/s 4064.8MB/s 6990.7MB/s WRITE: 3724.7MB/s 3772.1MB/s 6193.6MB/s READ: 1953.7MB/s 1967.3MB/s 2105.6MB/s WRITE: 1953.4MB/s 1966.7MB/s 2104.1MB/s READ: 1860.4MB/s 1897.4MB/s 2068.5MB/s WRITE: 1858.9MB/s 1895.9MB/s 2066.8MB/s jobs10 READ: 19730MB/s 19579MB/s 19492MB/s READ: 18028MB/s 18018MB/s 18221MB/s WRITE: 4027.3MB/s 4090.6MB/s 7020.1MB/s WRITE: 3810.5MB/s 3846.8MB/s 6426.8MB/s READ: 1956.1MB/s 1994.6MB/s 2145.2MB/s WRITE: 1955.9MB/s 1993.5MB/s 2144.8MB/s READ: 1852.8MB/s 1911.6MB/s 2075.8MB/s WRITE: 1855.7MB/s 1914.6MB/s 2078.1MB/s perf stat 4 streams 8 streams per-cpu ==================================================================================================================== jobs1 stalled-cycles-frontend 23,174,811,209 ( 38.21%) 23,220,254,188 ( 38.25%) 23,061,406,918 ( 38.34%) stalled-cycles-backend 11,514,174,638 ( 18.98%) 11,696,722,657 ( 19.27%) 11,370,852,810 ( 18.90%) instructions 73,925,005,782 ( 1.22) 73,903,177,632 ( 1.22) 73,507,201,037 ( 1.22) branches 14,455,124,835 ( 756.063) 14,455,184,779 ( 755.281) 14,378,599,509 ( 758.546) branch-misses 69,801,336 ( 0.48%) 80,225,529 ( 0.55%) 72,044,726 ( 0.50%) jobs2 stalled-cycles-frontend 49,912,741,782 ( 46.11%) 50,101,189,290 ( 45.95%) 32,874,195,633 ( 35.11%) stalled-cycles-backend 27,080,366,230 ( 25.02%) 27,949,970,232 ( 25.63%) 16,461,222,706 ( 17.58%) instructions 122,831,629,690 ( 1.13) 122,919,846,419 ( 1.13) 121,924,786,775 ( 1.30) branches 23,725,889,239 ( 692.663) 23,733,547,140 ( 688.062) 23,553,950,311 ( 794.794) branch-misses 90,733,041 ( 0.38%) 96,320,895 ( 0.41%) 84,561,092 ( 0.36%) jobs3 stalled-cycles-frontend 66,437,834,608 ( 45.58%) 63,534,923,344 ( 43.69%) 42,101,478,505 ( 33.19%) stalled-cycles-backend 34,940,799,661 ( 23.97%) 34,774,043,148 ( 23.91%) 21,163,324,388 ( 16.68%) instructions 171,692,121,862 ( 1.18) 171,775,373,044 ( 1.18) 170,353,542,261 ( 1.34) branches 32,968,962,622 ( 628.723) 32,987,739,894 ( 630.512) 32,729,463,918 ( 717.027) branch-misses 111,522,732 ( 0.34%) 110,472,894 ( 0.33%) 99,791,291 ( 0.30%) jobs4 stalled-cycles-frontend 98,741,701,675 ( 49.72%) 94,797,349,965 ( 47.59%) 54,535,655,381 ( 33.53%) stalled-cycles-backend 54,642,609,615 ( 27.51%) 55,233,554,408 ( 27.73%) 27,882,323,541 ( 17.14%) instructions 220,884,807,851 ( 1.11) 220,930,887,273 ( 1.11) 218,926,845,851 ( 1.35) branches 42,354,518,180 ( 592.105) 42,362,770,587 ( 590.452) 41,955,552,870 ( 716.154) branch-misses 138,093,449 ( 0.33%) 131,295,286 ( 0.31%) 121,794,771 ( 0.29%) jobs5 stalled-cycles-frontend 116,219,747,212 ( 48.14%) 110,310,397,012 ( 46.29%) 66,373,082,723 ( 33.70%) stalled-cycles-backend 66,325,434,776 ( 27.48%) 64,157,087,914 ( 26.92%) 32,999,097,299 ( 16.76%) instructions 270,615,008,466 ( 1.12) 270,546,409,525 ( 1.14) 268,439,910,948 ( 1.36) branches 51,834,046,557 ( 599.108) 51,811,867,722 ( 608.883) 51,412,576,077 ( 729.213) branch-misses 158,197,086 ( 0.31%) 142,639,805 ( 0.28%) 133,425,455 ( 0.26%) jobs6 stalled-cycles-frontend 138,009,414,492 ( 48.23%) 139,063,571,254 ( 48.80%) 75,278,568,278 ( 32.80%) stalled-cycles-backend 79,211,949,650 ( 27.68%) 79,077,241,028 ( 27.75%) 37,735,797,899 ( 16.44%) instructions 319,763,993,731 ( 1.12) 319,937,782,834 ( 1.12) 316,663,600,784 ( 1.38) branches 61,219,433,294 ( 595.056) 61,250,355,540 ( 598.215) 60,523,446,617 ( 733.706) branch-misses 169,257,123 ( 0.28%) 154,898,028 ( 0.25%) 141,180,587 ( 0.23%) jobs7 stalled-cycles-frontend 162,974,812,119 ( 49.20%) 159,290,061,987 ( 48.43%) 88,046,641,169 ( 33.21%) stalled-cycles-backend 92,223,151,661 ( 27.84%) 91,667,904,406 ( 27.87%) 44,068,454,971 ( 16.62%) instructions 369,516,432,430 ( 1.12) 369,361,799,063 ( 1.12) 365,290,380,661 ( 1.38) branches 70,795,673,950 ( 594.220) 70,743,136,124 ( 597.876) 69,803,996,038 ( 732.822) branch-misses 181,708,327 ( 0.26%) 165,767,821 ( 0.23%) 150,109,797 ( 0.22%) jobs8 stalled-cycles-frontend 185,000,017,027 ( 49.30%) 182,334,345,473 ( 48.37%) 99,980,147,041 ( 33.26%) stalled-cycles-backend 105,753,516,186 ( 28.18%) 107,937,830,322 ( 28.63%) 51,404,177,181 ( 17.10%) instructions 418,153,161,055 ( 1.11) 418,308,565,828 ( 1.11) 413,653,475,581 ( 1.38) branches 80,035,882,398 ( 592.296) 80,063,204,510 ( 589.843) 79,024,105,589 ( 730.530) branch-misses 199,764,528 ( 0.25%) 177,936,926 ( 0.22%) 160,525,449 ( 0.20%) jobs9 stalled-cycles-frontend 210,941,799,094 ( 49.63%) 204,714,679,254 ( 48.55%) 114,251,113,756 ( 33.96%) stalled-cycles-backend 122,640,849,067 ( 28.85%) 122,188,553,256 ( 28.98%) 58,360,041,127 ( 17.35%) instructions 468,151,025,415 ( 1.10) 467,354,869,323 ( 1.11) 462,665,165,216 ( 1.38) branches 89,657,067,510 ( 585.628) 89,411,550,407 ( 588.990) 88,360,523,943 ( 730.151) branch-misses 218,292,301 ( 0.24%) 191,701,247 ( 0.21%) 178,535,678 ( 0.20%) jobs10 stalled-cycles-frontend 233,595,958,008 ( 49.81%) 227,540,615,689 ( 49.11%) 160,341,979,938 ( 43.07%) stalled-cycles-backend 136,153,676,021 ( 29.03%) 133,635,240,742 ( 28.84%) 65,909,135,465 ( 17.70%) instructions 517,001,168,497 ( 1.10) 516,210,976,158 ( 1.11) 511,374,038,613 ( 1.37) branches 98,911,641,329 ( 585.796) 98,700,069,712 ( 591.583) 97,646,761,028 ( 728.712) branch-misses 232,341,823 ( 0.23%) 199,256,308 ( 0.20%) 183,135,268 ( 0.19%) per-cpu streams tend to cause significantly less stalled cycles; execute less branches and hit less branch-misses. perf stat reported execution time 4 streams 8 streams per-cpu ==================================================================== jobs1 seconds elapsed 20.909073870 20.875670495 20.817838540 jobs2 seconds elapsed 18.529488399 18.720566469 16.356103108 jobs3 seconds elapsed 18.991159531 18.991340812 16.766216066 jobs4 seconds elapsed 19.560643828 19.551323547 16.246621715 jobs5 seconds elapsed 24.746498464 25.221646740 20.696112444 jobs6 seconds elapsed 28.258181828 28.289765505 22.885688857 jobs7 seconds elapsed 32.632490241 31.909125381 26.272753738 jobs8 seconds elapsed 35.651403851 36.027596308 29.108024711 jobs9 seconds elapsed 40.569362365 40.024227989 32.898204012 jobs10 seconds elapsed 44.673112304 43.874898137 35.632952191 Please see Link: http://marc.info/?l=linux-kernel&m=146166970727530 Link: http://marc.info/?l=linux-kernel&m=146174716719650 for more test results (under low memory conditions). Signed-off-by: Sergey Senozhatsky Suggested-by: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

zram: pass gfp from zcomp frontend to backend

2016-01-15T19:40:51Z

Each zcomp backend uses own gfp flag but it's pointless because the context they could be called is driven by upper layer(ie, zcomp frontend). As well, zcomp frondend could call them in different context. One context(ie, zram init part) is it should be better to make sure successful allocation other context(ie, further stream allocation part for accelarating I/O speed) is just optional so let's pass gfp down from driver (ie, zcomp frontend) like normal MM convention. [sergey.senozhatsky@gmail.com: add missing __vmalloc zero and highmem gfps] Signed-off-by: Minchan Kim Signed-off-by: Sergey Senozhatsky Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

zram/zcomp: use GFP_NOIO to allocate streams

2016-01-15T19:40:51Z

We can end up allocating a new compression stream with GFP_KERNEL from within the IO path, which may result is nested (recursive) IO operations. That can introduce problems if the IO path in question is a reclaimer, holding some locks that will deadlock nested IOs. Allocate streams and working memory using GFP_NOIO flag, forbidding recursive IO and FS operations. An example: inconsistent {IN-RECLAIM_FS-W} -> {RECLAIM_FS-ON-W} usage. git/20158 [HC0[0]:SC0[0]:HE1:SE1] takes: (jbd2_handle){+.+.?.}, at: start_this_handle+0x4ca/0x555 {IN-RECLAIM_FS-W} state was registered at: __lock_acquire+0x8da/0x117b lock_acquire+0x10c/0x1a7 start_this_handle+0x52d/0x555 jbd2__journal_start+0xb4/0x237 __ext4_journal_start_sb+0x108/0x17e ext4_dirty_inode+0x32/0x61 __mark_inode_dirty+0x16b/0x60c iput+0x11e/0x274 __dentry_kill+0x148/0x1b8 shrink_dentry_list+0x274/0x44a prune_dcache_sb+0x4a/0x55 super_cache_scan+0xfc/0x176 shrink_slab.part.14.constprop.25+0x2a2/0x4d3 shrink_zone+0x74/0x140 kswapd+0x6b7/0x930 kthread+0x107/0x10f ret_from_fork+0x3f/0x70 irq event stamp: 138297 hardirqs last enabled at (138297): debug_check_no_locks_freed+0x113/0x12f hardirqs last disabled at (138296): debug_check_no_locks_freed+0x33/0x12f softirqs last enabled at (137818): __do_softirq+0x2d3/0x3e9 softirqs last disabled at (137813): irq_exit+0x41/0x95 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(jbd2_handle); lock(jbd2_handle); *** DEADLOCK *** 5 locks held by git/20158: #0: (sb_writers#7){.+.+.+}, at: [] mnt_want_write+0x24/0x4b #1: (&type->i_mutex_dir_key#2/1){+.+.+.}, at: [] lock_rename+0xd9/0xe3 #2: (&sb->s_type->i_mutex_key#11){+.+.+.}, at: [] lock_two_nondirectories+0x3f/0x6b #3: (&sb->s_type->i_mutex_key#11/4){+.+.+.}, at: [] lock_two_nondirectories+0x66/0x6b #4: (jbd2_handle){+.+.?.}, at: [] start_this_handle+0x4ca/0x555 stack backtrace: CPU: 2 PID: 20158 Comm: git Not tainted 4.1.0-rc7-next-20150615-dbg-00016-g8bdf555-dirty #211 Call Trace: dump_stack+0x4c/0x6e mark_lock+0x384/0x56d mark_held_locks+0x5f/0x76 lockdep_trace_alloc+0xb2/0xb5 kmem_cache_alloc_trace+0x32/0x1e2 zcomp_strm_alloc+0x25/0x73 [zram] zcomp_strm_multi_find+0xe7/0x173 [zram] zcomp_strm_find+0xc/0xe [zram] zram_bvec_rw+0x2ca/0x7e0 [zram] zram_make_request+0x1fa/0x301 [zram] generic_make_request+0x9c/0xdb submit_bio+0xf7/0x120 ext4_io_submit+0x2e/0x43 ext4_bio_write_page+0x1b7/0x300 mpage_submit_page+0x60/0x77 mpage_map_and_submit_buffers+0x10f/0x21d ext4_writepages+0xc8c/0xe1b do_writepages+0x23/0x2c __filemap_fdatawrite_range+0x84/0x8b filemap_flush+0x1c/0x1e ext4_alloc_da_blocks+0xb8/0x117 ext4_rename+0x132/0x6dc ? mark_held_locks+0x5f/0x76 ext4_rename2+0x29/0x2b vfs_rename+0x540/0x636 SyS_renameat2+0x359/0x44d SyS_rename+0x1e/0x20 entry_SYSCALL_64_fastpath+0x12/0x6f [minchan@kernel.org: add stable mark] Signed-off-by: Sergey Senozhatsky Acked-by: Minchan Kim Cc: Kyeongdon Kim Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

zram: fix possible use after free in zcomp_create()

2015-09-18T04:16:07Z

zcomp_create() verifies the success of zcomp_strm_{multi,single}_create() through comp->stream, which can potentially be pointing to memory that was freed if these functions returned an error. While at it, replace a 'ERR_PTR(-ENOMEM)' by a more generic 'ERR_PTR(error)' as in the future zcomp_strm_{multi,siggle}_create() could return other error codes. Function documentation updated accordingly. Fixes: beca3ec71fe5 ("zram: add multi stream functionality") Signed-off-by: Luis Henriques Acked-by: Sergey Senozhatsky Acked-by: Minchan Kim Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

zram: check comp algorithm availability earlier

2015-06-26T00:00:37Z

Improvement idea by Marcin Jabrzyk. comp_algorithm_store() silently accepts any supplied algorithm name, because zram performs algorithm availability check later, during the device configuration phase in disksize_store() and emits the following error: "zram: Cannot initialise %s compressing backend" this error line is somewhat generic and, besides, can indicate a failed attempt to allocate compression backend's working buffers. add algorithm availability check to comp_algorithm_store(): echo lzz > /sys/block/zram0/comp_algorithm -bash: echo: write error: Invalid argument Signed-off-by: Sergey Senozhatsky Reported-by: Marcin Jabrzyk Acked-by: Minchan Kim Cc: Nitin Gupta Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

zram: cut trailing newline in algorithm name

2015-06-26T00:00:36Z

Supplied sysfs values sometimes contain new-line symbols (echo vs. echo -n), which we also copy as a compression algorithm name. it works fine when we lookup for compression algorithm, because we use sysfs_streq() which takes care of new line symbols. however, it doesn't look nice when we print compression algorithm name if zcomp_create() failed: zram: Cannot initialise LXZ compressing backend cut trailing new-line, so the error string will look like zram: Cannot initialise LXZ compressing backend we also now can replace sysfs_streq() in zcomp_available_show() with strcmp(). Signed-off-by: Sergey Senozhatsky Cc: Minchan Kim Cc: Nitin Gupta Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

zram: use scnprintf() in attrs show() methods

2014-04-07T23:36:02Z

sysfs.txt documentation lists the following requirements: - The buffer will always be PAGE_SIZE bytes in length. On i386, this is 4096. - show() methods should return the number of bytes printed into the buffer. This is the return value of scnprintf(). - show() should always use scnprintf(). Use scnprintf() in show() functions. Signed-off-by: Sergey Senozhatsky Acked-by: Minchan Kim Cc: Jerome Marchand Cc: Nitin Gupta Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

zram: propagate error to user

2014-04-07T23:36:02Z

When we initialized zcomp with single, we couldn't change max_comp_streams without zram reset but current interface doesn't show any error to user and even it changes max_comp_streams's value without any effect so it would make user very confusing. This patch prevents max_comp_streams's change when zcomp was initialized as single zcomp and emit the error to user(ex, echo). [akpm@linux-foundation.org: don't return with the lock held, per Sergey] [fengguang.wu@intel.com: fix coccinelle warnings] Signed-off-by: Minchan Kim Cc: Nitin Gupta Cc: Jerome Marchand Acked-by: Sergey Senozhatsky Signed-off-by: Fengguang Wu Cc: Stephen Rothwell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

zram: return error-valued pointer from zcomp_create()

2014-04-07T23:36:02Z

Instead of returning just NULL, return ERR_PTR from zcomp_create() if compressing backend creation has failed. ERR_PTR(-EINVAL) for unsupported compression algorithm request, ERR_PTR(-ENOMEM) for allocation (zcomp or compression stream) error. Perform IS_ERR() check of returned from zcomp_create() value in disksize_store() and set return code to PTR_ERR(). Change suggested by Jerome Marchand. [akpm@linux-foundation.org: clean up error recovery flow] Signed-off-by: Sergey Senozhatsky Reported-by: Jerome Marchand Cc: Minchan Kim Cc: Nitin Gupta Cc: Arnd Bergmann Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds