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author | Eric Sandeen <sandeen@redhat.com> | 2012-04-30 18:11:29 (GMT) |
---|---|---|
committer | Al Viro <viro@zeniv.linux.org.uk> | 2012-07-22 20:00:15 (GMT) |
commit | e8b96eb5034a0ccebf36760f88e31ea3e3cdf1e4 (patch) | |
tree | 3ea1b85311b3d059f2bbf38e484aa2ce06bab017 | |
parent | 4ea425b63a3dfeb7707fc7cc7161c11a51e871ed (diff) | |
download | linux-e8b96eb5034a0ccebf36760f88e31ea3e3cdf1e4.tar.xz |
vfs: allow custom EOF in generic_file_llseek code
For ext3/4 htree directories, using the vfs llseek function with
SEEK_END goes to i_size like for any other file, but in reality
we want the maximum possible hash value. Recent changes
in ext4 have cut & pasted generic_file_llseek() back into fs/ext4/dir.c,
but replicating this core code seems like a bad idea, especially
since the copy has already diverged from the vfs.
This patch updates generic_file_llseek_size to accept
both a custom maximum offset, and a custom EOF position. With this
in place, ext4_dir_llseek can pass in the appropriate maximum hash
position for both maxsize and eof, and get what it wants.
As far as I know, this does not fix any bugs - nfs in the kernel
doesn't use SEEK_END, and I don't know of any user who does. But
some ext4 folks seem keen on doing the right thing here, and I can't
really argue.
(Patch also fixes up some comments slightly)
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r-- | fs/ext3/dir.c | 3 | ||||
-rw-r--r-- | fs/ext4/file.c | 3 | ||||
-rw-r--r-- | fs/read_write.c | 18 | ||||
-rw-r--r-- | include/linux/fs.h | 2 |
4 files changed, 15 insertions, 11 deletions
diff --git a/fs/ext3/dir.c b/fs/ext3/dir.c index 92490e9..901f67e 100644 --- a/fs/ext3/dir.c +++ b/fs/ext3/dir.c @@ -303,7 +303,8 @@ loff_t ext3_dir_llseek(struct file *file, loff_t offset, int origin) if (likely(dx_dir)) return generic_file_llseek_size(file, offset, origin, - ext3_get_htree_eof(file)); + ext3_get_htree_eof(file), + i_size_read(inode)); else return generic_file_llseek(file, offset, origin); } diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 8c7642a..f3dadd0 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -225,7 +225,8 @@ loff_t ext4_llseek(struct file *file, loff_t offset, int origin) else maxbytes = inode->i_sb->s_maxbytes; - return generic_file_llseek_size(file, offset, origin, maxbytes); + return generic_file_llseek_size(file, offset, origin, + maxbytes, i_size_read(inode)); } const struct file_operations ext4_file_operations = { diff --git a/fs/read_write.c b/fs/read_write.c index c20614f..1adfb69 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -55,10 +55,11 @@ static loff_t lseek_execute(struct file *file, struct inode *inode, * @file: file structure to seek on * @offset: file offset to seek to * @origin: type of seek - * @size: max size of file system + * @size: max size of this file in file system + * @eof: offset used for SEEK_END position * * This is a variant of generic_file_llseek that allows passing in a custom - * file size. + * maximum file size and a custom EOF position, for e.g. hashed directories * * Synchronization: * SEEK_SET and SEEK_END are unsynchronized (but atomic on 64bit platforms) @@ -67,13 +68,13 @@ static loff_t lseek_execute(struct file *file, struct inode *inode, */ loff_t generic_file_llseek_size(struct file *file, loff_t offset, int origin, - loff_t maxsize) + loff_t maxsize, loff_t eof) { struct inode *inode = file->f_mapping->host; switch (origin) { case SEEK_END: - offset += i_size_read(inode); + offset += eof; break; case SEEK_CUR: /* @@ -99,7 +100,7 @@ generic_file_llseek_size(struct file *file, loff_t offset, int origin, * In the generic case the entire file is data, so as long as * offset isn't at the end of the file then the offset is data. */ - if (offset >= i_size_read(inode)) + if (offset >= eof) return -ENXIO; break; case SEEK_HOLE: @@ -107,9 +108,9 @@ generic_file_llseek_size(struct file *file, loff_t offset, int origin, * There is a virtual hole at the end of the file, so as long as * offset isn't i_size or larger, return i_size. */ - if (offset >= i_size_read(inode)) + if (offset >= eof) return -ENXIO; - offset = i_size_read(inode); + offset = eof; break; } @@ -132,7 +133,8 @@ loff_t generic_file_llseek(struct file *file, loff_t offset, int origin) struct inode *inode = file->f_mapping->host; return generic_file_llseek_size(file, offset, origin, - inode->i_sb->s_maxbytes); + inode->i_sb->s_maxbytes, + i_size_read(inode)); } EXPORT_SYMBOL(generic_file_llseek); diff --git a/include/linux/fs.h b/include/linux/fs.h index 6a6ca85..34acf51 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2454,7 +2454,7 @@ extern loff_t noop_llseek(struct file *file, loff_t offset, int origin); extern loff_t no_llseek(struct file *file, loff_t offset, int origin); extern loff_t generic_file_llseek(struct file *file, loff_t offset, int origin); extern loff_t generic_file_llseek_size(struct file *file, loff_t offset, - int origin, loff_t maxsize); + int origin, loff_t maxsize, loff_t eof); extern int generic_file_open(struct inode * inode, struct file * filp); extern int nonseekable_open(struct inode * inode, struct file * filp); |