Eric Lee / smarc-fsl-linux-kernel

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Commit 2bdf67eb1631f30e2f3f5d49e4007c76e88877a8

Authored by OGAWA Hirofumi
Committed by Linus Torvalds
1 parent 0e75f5da06
Exists in master and in 39 other branches 8mp-imx_5.4.70_2.3.0, 8qm-imx_5.4.70_2.3.0, emb_imx_lf-5.15.y, emb_lf-6.1.y, imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, imx_4.1.15_1.0.0_ga, pitx_8mp_lf-5.10.y, rt-smarc-imx_4.1.15_1.0.0_ga, rt_linux_5.15.71, smarc-8m-android-11.0.0_2.0.0, smarc-imx6_4.14.98_2.0.0_ga, smarc-imx6_4.9.88_2.0.0_ga, smarc-imx7_4.14.98_2.0.0_ga, smarc-imx7_4.9.11_1.0.0_ga, smarc-imx7_4.9.88_2.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-imx_4.1.15_1.0.0_ga, smarc-imx_4.9.11_1.0.0_ga, smarc-imx_4.9.51_imx8m_ga, smarc-imx_4.9.88_2.0.0_ga, smarc-m6.0.1_2.1.0-ga, smarc-n7.1.2_2.0.0-ga, smarc-rel_imx_4.1.15_1.2.0_ga, smarc_8m_00d0_imx_4.14.98_2.0.0_ga, smarc_8m_imx_4.14.78_1.0.0_ga, smarc_8m_imx_4.14.98_2.0.0_ga, smarc_8m_imx_4.19.35_1.1.0, smarc_8mm_imx_4.14.78_1.0.0_ga, smarc_8mm_imx_4.14.98_2.0.0_ga, smarc_8mm_imx_4.19.35_1.1.0, smarc_8mm_imx_5.4.24_2.1.0, smarc_8mp_lf-5.10.y, smarc_8mq_imx_5.4.24_2.1.0, smarc_8mq_lf-5.10.y, smarc_imx_lf-5.15.y

fat: mmu_private race fix 

mmu_private is 64bits value, hence it's not atomic to update.

So, the access rule for mmu_private is we must hold ->i_mutex.  But,
fat_get_block() path doesn't follow the rule on non-allocation path.

This fixes by using i_size instead if non-allocation path.

Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Showing 4 changed files with 25 additions and 10 deletions Side-by-side Diff

... ... @@ -293,10 +293,12 @@
293 293 }
294 294  
295 295 int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
296   - unsigned long *mapped_blocks)
  296 + unsigned long *mapped_blocks, int create)
297 297 {
298 298 struct super_block *sb = inode->i_sb;
299 299 struct msdos_sb_info *sbi = MSDOS_SB(sb);
  300 + const unsigned long blocksize = sb->s_blocksize;
  301 + const unsigned char blocksize_bits = sb->s_blocksize_bits;
300 302 sector_t last_block;
301 303 int cluster, offset;
302 304  
... ... @@ -309,10 +311,21 @@
309 311 }
310 312 return 0;
311 313 }
312   - last_block = (MSDOS_I(inode)->mmu_private + (sb->s_blocksize - 1))
313   - >> sb->s_blocksize_bits;
314   - if (sector >= last_block)
315   - return 0;
  314 +
  315 + last_block = (i_size_read(inode) + (blocksize - 1)) >> blocksize_bits;
  316 + if (sector >= last_block) {
  317 + if (!create)
  318 + return 0;
  319 +
  320 + /*
  321 + * ->mmu_private can access on only allocation path.
  322 + * (caller must hold ->i_mutex)
  323 + */
  324 + last_block = (MSDOS_I(inode)->mmu_private + (blocksize - 1))
  325 + >> blocksize_bits;
  326 + if (sector >= last_block)
  327 + return 0;
  328 + }
316 329  
317 330 cluster = sector >> (sbi->cluster_bits - sb->s_blocksize_bits);
318 331 offset = sector & (sbi->sec_per_clus - 1);
... ... @@ -77,7 +77,7 @@
77 77  
78 78 *bh = NULL;
79 79 iblock = *pos >> sb->s_blocksize_bits;
80   - err = fat_bmap(dir, iblock, &phys, &mapped_blocks);
  80 + err = fat_bmap(dir, iblock, &phys, &mapped_blocks, 0);
81 81 if (err || !phys)
82 82 return -1; /* beyond EOF or error */
83 83  
... ... @@ -91,7 +91,9 @@
91 91 /* for avoiding the race between fat_free() and fat_get_cluster() */
92 92 unsigned int cache_valid_id;
93 93  
94   - loff_t mmu_private;
  94 + /* NOTE: mmu_private is 64bits, so must hold ->i_mutex to access */
  95 + loff_t mmu_private; /* physically allocated size */
  96 +
95 97 int i_start; /* first cluster or 0 */
96 98 int i_logstart; /* logical first cluster */
97 99 int i_attrs; /* unused attribute bits */
... ... @@ -222,7 +224,7 @@
222 224 extern int fat_get_cluster(struct inode *inode, int cluster,
223 225 int *fclus, int *dclus);
224 226 extern int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
225   - unsigned long *mapped_blocks);
  227 + unsigned long *mapped_blocks, int create);
226 228  
227 229 /* fat/dir.c */
228 230 extern const struct file_operations fat_dir_operations;
... ... @@ -64,7 +64,7 @@
64 64 sector_t phys;
65 65 int err, offset;
66 66  
67   - err = fat_bmap(inode, iblock, &phys, &mapped_blocks);
  67 + err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create);
68 68 if (err)
69 69 return err;
70 70 if (phys) {
... ... @@ -94,7 +94,7 @@
94 94 *max_blocks = min(mapped_blocks, *max_blocks);
95 95 MSDOS_I(inode)->mmu_private += *max_blocks << sb->s_blocksize_bits;
96 96  
97   - err = fat_bmap(inode, iblock, &phys, &mapped_blocks);
  97 + err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create);
98 98 if (err)
99 99 return err;
100 100